My intuition tells me to go with old timers. Gabin and Fonda have unique longevity and adaptability on their side, while Hanks' career has been pretty stagnant for a while bar a few expections. All three are cultural icons of course, with Gabin's iconic status mostly limited to Europe but huge there.

1. Cary Grant
2. Henry Fonda
3. Jean Gabin
4. Dustin Hoffman
5. Alec Guinness
6. Gérard Depardieu
7. Tom Hanks
8. Clark Gable
9. Kirk Douglas
10. Gene Hackman
11. William Holden
12. Morgan Freeman
13. Clint Eastwood
14. Leonardo DiCaprio
15. Vittorio Gassman
16. Anthony Hopkins
17. Phillip Seymour Hoffman
18. Dennis Hopper
19. Richard Harris
20. Robert Duvall
21. Harrison Ford
22. Douglas Fairbanks
23. Emil Jannings
24. John Hurt
25. Raj Kapoor
26. Johnny Depp
27. Errol Flynn
28. Charlton Heston
29. Samuel L. Jackson
30. Rock Hudson
31. Albert Finney
32. Sessue Hayakawa
33. Jeremy Irons
34. Erland Josephson
35. Ralph Fiennes
36. John Gielgud
37. Michael Douglas
38. Peter Finch
39. Richard Dreyfuss
40. W.C. Fields
41. José Vicente Ferrer
42. Bruno Ganz
43. John Gilbert
44. Melvyn Douglas
45. Mel Gibson
46. William Hurt
47. William S. Hart
48. Ed Harris
49. Tommy Lee Jones
50. Robert Downey Jr.
51. Robert Donat
52. Giancarlo Giannini
53. Ryan Gosling
54. Bob Hope
55. Walter Huston
56. Rex Harrison
57. James Earl Jones
58. Gael Garcia Bernal
59. Jake Gyllenhaal
60. Bob Hoskins
61. Brendan Gleeson
62. Leslie Howard
63. Edward Everett Horton
64. Sterling Hayden
65. Rutger Hauer
66. Curd Jürgens
67. Michael Fassbender
68. John Goodman
69. Bruce Dern
70. Aldo Fabrizi
71. Ian Holm
72. Sydney Greenstreet
73. Colin Firth
74. Chiwetel Ejiofor
75. Alan Hale Sr.

For me, Gabin deserves to be in the Top 3. He is to France what Mastroianni is to Italy and Mifune is to Japan. His body of work and peak (more than two decades of absolute success) are also greater than Hoffman's. Some of his movie quotes - such as "T'as de beaux yeux, tu sais" and "Salauds de pauvres" - have become part of the French popular culture, so that gives him some cultural recognition as well. The only criterion where Hoffman clearly wins is popularity.

I also think Depardieu should be ahead of Hanks. Depardieu is internationally acclaimed as France's greatest modern actor. Gégé is also in TSPDT's shooting gallery list, Hanks isn't. He has also some influence as well with introducing a "physical" style of playing to French cinema that was very different from either the theatrical acting of the 50's or the 60's method acting. Hanks will take cultural impact and popularity (although both are very popular all over the world).

I am also still not comfortable with DiCaprio>Gassman, Gassman easily wins acclaim and influence. He is the most decorated Italian actor of all time (yes, more than Mastroianni) and the most prominant figure of a talented generation of Italian actors who introduced modern theater theory to movie acting. The only advantage that Marcello has on him is the international recognition that comes with working with the likes of Fellini and Antonioni, while Gassman prefered to work with more "national" directors such as Dino Risi, Mario Monicelli and Ettore Scola. In my opinion, there shouldn't be a huge gap between the two Italians.

I don't know about Gabin over Hoffman, AyaMelie. In addition to his popularity, Hoffman is also extremely acclaimed and quite influential. His body of work is not too shabby at all: Graduate, Midnight Cowboy, All the President's Men, Kramer vs Kramer, Tootsie, Rain Man are all classics of American cinema.
I think few actors on list combine popularity with acclaim better than Hanks does. While Depardieu is greatest modern French actor, you can make a case for Hanks as greatest modern American actor, like pave did for Washington.
And finally, I don't disagree on Gassman, but DiCaprio is modern great as well. I think if we can credit Gassman with significant influence on Italian acting, he takes this matchup overall.

Time for some sort of compromise.

1. Cary Grant
2. Dustin Hoffman
3. Henry Fonda
4. Alec Guinness
5. Jean Gabin
6. Tom Hanks
7. Gérard Depardieu
8. Gene Hackman
9. Clark Gable
10. Kirk Douglas
11. Morgan Freeman
12. Clint Eastwood
13. William Holden
14. Leonardo DiCaprio
15. Vittorio Gassman
16. Robert Duvall
17. Anthony Hopkins
18. Harrison Ford
19. Philip Seymour Hoffman
20. Dennis Hopper
21. Douglas Fairbanks
22. Johnny Depp
23. Errol Flynn
24. Richard Harris
25. Albert Finney
26. Ralph Fiennes
27. John Gielgud
28. Emil Jannings
29. John Hurt
30. Raj Kapoor
31. Charlton Heston
32. Samuel L. Jackson
33. Michael Douglas
34. Rock Hudson
35. Peter Finch
36. Sessue Hayakawa
37. Jeremy Irons
38. Erland Josephson
39. William Hurt
40. Richard Dreyfuss
41. William S. Hart
42. W.C. Fields
43. Ed Harris
44. Tommy Lee Jones
45. José Ferrer
46. Bruno Ganz
47. John Gilbert
48. Ryan Gosling
49. Melvyn Douglas
50. Bob Hope
51. Walter Huston
52. Mel Gibson
53. Rex Harrison
54. James Earl Jones
55. Robert Downey, Jr.
56. Jake Gyllenhaal
57. Robert Donat
58. Giancarlo Giannini
59. Bob Hoskins
60. Gael García Bernal
61. Brendan Gleeson
62. Leslie Howard
63. Edward Everett Horton
64. Sterling Hayden
65. Rutger Hauer
66. Michael Fassbender
67. Curd Jürgens
68. John Goodman
69. Bruce Dern
70. Aldo Fabrizi
71. Ian Holm
72. Colin Firth
73. Sydney Greenstreet
74. Alan Hale, Sr.
75. Chiwetel Ejiofor

Something like this? I'm curious why you put Richard Harris so high, AyaMelie. His body of work is pretty weak, he was reasonably popular during the 1960s (but that's about it). He maybe takes some influence for his role in This Sporting Life, and overall he is rather acclaimed (but it's not like he scores very big there). That's why I put him below more acclaimed British actors with a stronger body of work like Finney, Fiennes and Gielgud. But if more agree on having him ahead of them, I'll have to agree as well.

I would personally have John Hurt couple of spots higher, very acclaimed and strong body of work, with focus on supporting roles. Maybe something like this:

25. Emil Jannings
26. John Hurt
27. Albert Finney
28. Ralph Fiennes
29. John Gielgud

Looks good, but I still don't support Harris being ahead of these other British icons. Maybe it's time for a little comparison between Harris, Hurt, Finney, Fiennes and Gielgud.

Acclaim (film work only)
Richard Harris
Academy Award nominations: 2
Academy Award wins: 0

Golden Globe nominations: 2
Golden Globe wins: 1

BAFTA nominations: 1
BAFTA wins: 0

John Hurt
Academy Award nominations: 2
Academy Award wins: 0

Golden Globe nominations: 2
Golden Globe wins: 1

BAFTA nominations: 5
BAFTA wins: 1

Hurt also received an award for Outstanding British Contribution to Cinema in 2012 at the BAFTAs.

Albert Finney
Academy Award nominations: 5
Academy Award wins: 0

Golden Globe nominations: 7
Golden Globe wins: 1

BAFTA nominations: 8
BAFTA wins: 0

Finney also received Most Promising Newcomer-awards at the BAFTAs in 1961 and the Golden Globes in 1964 and received the Academy Fellowship from the BAFTAs in 2001.

Ralph Fiennes
Academy Award nominations: 2
Academy Award wins: 0

Golden Globe nominations: 4
Golden Globe wins: 0

BAFTA nominations: 5
BAFTA wins: 1

John Gielgud
Academy Award nominations: 2
Academy Award wins: 1

Golden Globe nominations: 1
Golden Globe wins: 1

BAFTA nominations: 5
BAFTA wins: 2

Gielgud also received the Academy Fellowship at the BAFTAs in 1992.

Order of acclaim:
1. Albert Finney
2. Ralph Fiennes
3. John Hurt
4. John Gielgud
5. Richard Harris

Influence
- Richard Harris has no clear influence, but This Sporting Life is an important British 'kitchen sink'-drama.
- John Hurt has no clear influence.
- Albert Finney was a more important 'kitchen sink'-actor than Harris, appearing in Saturday Night and Sunday Morning and Tom Jones.
- Ralph Fiennes also has no clear influence.
- John Gielgud was, with Ralph Richardson and Laurence Olivier, he one of the trio of actors who dominated the British stage for much of the 20th century, but he also, like Olivier took stage acting into the film industry.

Order of influence:
1. John Gielgud
2. Albert Finney
3. Richard Harris
4. John Hurt/Ralph Fiennes

Body of work
Richard Harris
The Guns of Navarone (1961)
Mutiny on the Bounty (1962)
This Sporting Life (1963)
Red Desert (1964)
Cromwell (1970)
A Man Called Horse (1970)
The Molly Maguires (1970)
The Field (1990)
Unforgiven (1992)
Wrestling Ernest Hemingway (1993)
The Barber of Siberia (1998)
Gladiator (2000)
Harry Potter and the Philosopher's Stone (2001)
The Count of Monte Cristo (2002)
Harry Potter and the Chamber of Secrets (2002)

In his later years, Harris often played minor supporting roles. As we can see, the 1970s and 1980s are forgettable decades for him, and he didn't play huge parts in later classics like Unforgiven and Gladiator.

John Hurt
A Man for All Seasons (1966)
10 Rillington Place (1971)
Midnight Express (1978)
Alien (1979)
The Elephant Man (1980)
The Hit (1984)
Nineteen Eighty-Four (1984)
The Field (1990)
Dead Man (1995)
Rob Roy (1995)
Contact (1997)
Love and Death on Long Island (1997)
The Harry Potter-franchise (2001-2011)
Dogville (narrator, 2003)
Owning Mahowny (2003)
Hellboy (2004)
The Proposition (2005)
Shooting Dogs (2005)
V for Vendetta (2006)
An Englishman in New York (2009)
Melancholia (2011)
Tinker Tailor Soldier Spy (2011)
Only Lovers Left Alive (2013)
Snowpiercer (2013)
Jackie (2016)

Impressive. Sometimes in smaller roles, but more often in vital supporting parts, Hurt established a great body of work.

Albert Finney
The Entertainer (1960)
Saturday Night and Sunday Morning (1960)
Tom Jones (1963)
Two for the Road (1967)
Scrooge (1970)
Murder on the Orient Express (1974)
The Duellists (1977)
Shoot the Moon (1982)
The Dresser (1983)
Under the Volcano (1984)
Miller's Crossing (1990)
The Browning Version (1994)
Erin Brockovich (2000)
Traffic (2000)
Big Fish (2003)
Amazing Grace (2006)
A Good Year (2006)
Before the Devil Knows You're Dead (2007)
The Bourne Ultimatum (2007)
Skyfall (2012)

Ralph Fiennes
Schindler's List (1993)
Quiz Show (1994)
Strange Days (1995)
The English Patient (1996)
The End of the Affair (1999)
Sunshine (1999)
Red Dragon (2002)
The Constant Gardener (2005)
The Harry Potter-franchise (2005-2011)
The Duchess (2008)
In Bruges (2008)
The Reader (2008)
The Hurt Locker (2009)
Skyfall (2012)
The Grand Budapest Hotel (2014)

Despite the fact that he started in the early 1990s, Fiennes already has a very strong filmography.

John Gielgud
Julius Caesar (1953)
Richard III (1955)
Becket (1964)
Chimes at Midnight (1965)
The Loved One (1965)
The Shoes of the Fisherman (1968)
Oh! What a Lovely War (1969)
Murder on the Orient Express (1974)
Providence (1977)
Murder by Decree (1979)
The Elephant Man (1980)
Arthur (1981)
Chariots of Fire (1981)
Lion of the Desert (1981)
Gandhi (1982)
The Shooting Party (1985)
The Power of One (1992)
Hamlet (1996)
Shine (1996)
Elizabeth (1998)

Gielgud acted in a lot of great films, but quite often in very small roles, sometimes even limited to one scene. I guess name-dropping his films might seem impressive, but his roles in a lot of these aren't.

Order of body of work:
1. John Hurt
2. Albert Finney
3. Ralph Fiennes
4. John Gielgud/Richard Harris

Popularity and cultural recognition
- Richard Harris was quite popular during the 1960s, and acted in some commercial hits (together with earlier-mentioned films, these include Hawaii and Camelot). Harris received the most cultural recognition for his role as Albus Dumbledore in the first two Harry Potter-films, but after his death, he was aptly replaced by Michael Gambon; I have the feeling that many see him as the 'true' Dumbledore, because he acted in more films and Dumbledore's part got more important towards the end. He is of course also well-known for his song 'MacArthur Park,' but that is of no importance here.
- John Hurt was noted for his voice, which he often used for narration in films; for example the aforementioned Dogville, but also in Manderlay, Perfume: The Story of a Murderer and several documentaries. He also used his voice in animated films such as Watership Down, The Plague Dogs and The Black Cauldron. Hurt also played Mr. Ollivander in the Harry Potter-films. His most famous scene is of course in Alien, where the creature bursts out of his chest.
- Albert Finney was quite popular during the 1960s, especially thanks to his role in Tom Jones. He is less 'culturally recognized' nowadays because he acted in a lot of films that parts of the modern audience probably haven't seen. Nevertheless, Finney is probably the most popular and well-known Hercule Poirot on film (we'll have to wait if Kenneth Branagh will surpass him in the new adaptation, coming out this year).
- Ralph Fiennes has one of the more recognizable voices in modern films. He is incredibly popular and became some sort of a cultural icon through his amazing villainous roles in Schindler's List and the Harry Potter-franchise, as Voldemort. Furthermore, The English Patient was one of the most popular 'women's films' of the 1990s.
- John Gielgud is probably not very culturally recognizable and popular. As I stated above, his roles were often small, and he is virtually unknown to many popular film audiences. Probably more renowned for his stage work. However, he was culturally recognizable in the 1950s, when he was convicted and fined for a homosexual offence. He was one of the few who came out for their homosexuality in these days.

Order of popularity/cultural recognition:
1. Ralph Fiennes
2. John Hurt
3. Albert Finney
4. Richard Harris
5. John Gielgud

I guess my overal order of these five would be:
1. Albert Finney
2. John Hurt
3. Ralph Fiennes
4. Richard Harris
5. John Gielgud

I think he influenced Italian acting with his dramatic reading of lines, a la Olivier. Also, and after shooting Scent of a Woman, Al Pacino spoke about the big influence of Gassman on his career and called him an "idol".

I think Harris should be higher in your cultural recognition list, Luuk. Most HP fan forums still consider him as the "real" Dumbledore, which is remarkable given the fact that he only starred in the first two movies. Even JK Rowling praised his performance and said that she couldn't have imagined a better Albus Dumbledore (she never said the same about Michael). Gambon was often criticized for his over-acting and some real "un-Dumbledory" enthusiasm and frenzy that fans found unnecessary and very uncharacteristic of Albus.
Harris also gets some cultural recognition for his legendary friendship with the other "hell-raising", British actor Peter O'Toole.

Gassman vs. DiCaprio

In terms of acclaim, it's true that Gassman is the most decorated Italian actor, certainly domestically. But on the other hand, DiCaprio is certainly one of the most acclaimed and celebrated American actors of the last 25 years. Everybody knew how he was due to win an Oscar for The Revenant, because many film critics and fans thought he should've won earlier. DiCaprio already has 5 Oscar nominations + 1 win, and he's only 42 years old. I think, if he goes on like this, he will become one of the biggest American actors of all time.

Gassman wins influence, there's probably no debate about that; DiCaprio doesn't have that much influence YET, but this could change. He's probably the De Niro of his generation, which could influence actors of later generations. That's hypothetical, though.

I think DiCaprio wins in body of work. You're right, AyaMelie, Mastroianni made more films for the international market, whereas Gassman focused on the Italian audiences. Some of his films reached international audiences, you already named Scent of a Woman. Also Big Deal on Madonna Street, The Great War, Il Sorpasso and We All Loved Each Other So Much. But DiCaprio's filmography reads as a best of-list of the past 25 years: This Boy's Life, What's Eating Gilbert Grape, Romeo + Juliet, Titanic, Catch Me If You Can, Gangs of New York, The Aviator, Blood Diamond, The Departed, Body of Lies, Revolutionary Road, Inception, Shutter Island, Django Unchained, The Great Gatsby, The Wolf of Wall Street, The Revenant. It's hard to top that.

And I think that DiCaprio wins popularity. One of the best-known film stars of the world at the moment, and the 'Leomania' after the release of Titanic was almost never seen before. I think it came close to the worldwide popularity of Chaplin in his early days. This might seem exaggerated, but everybody watched Titanic at the time, making it by far the highest grossing film of all time at that moment, and everybody knew Leo because of this. Here in the Netherlands and Belgium, there was even a girl group singing songs about him...

OK, but will this make him jump ahead of Fiennes? Not in my opinion.

24. Albert Finney
25. John Hurt
26. Emil Jannings
27. Ralph Fiennes
28. Richard Harris
29. John Gielgud

How about this for that segment of the list?

I suggest this:

24. Richard Harris
25. Albert Finney
26. Ralph Fiennes
27. John Gielgud
28. Emil Jannings
29. John Hurt
30. Raj Kapoor
31. Charlton Heston

becoming this:

24. Albert Finney
25. Emil Jannings
26. John Hurt
27. Ralph Fiennes
28. Richard Harris
29. Raj Kapoor
30. Charlton Heston
31. John Gielgud

Yeah that looks right.

What do you guys think?

1. Laurence Olivier 
2. Paul Newman
3. Toshiro Mifune
4. Jack Nicholson
5. Al Pacino
6. Marcello Mastroianni
7. Buster Keaton
8. Jack Lemmon
9. Gregory Peck
10. Peter O'Toole
11. Burt Lancaster
12. Robert Mitchum
13. Harold Lloyd
14. Michel Piccoli
15. Sean Penn
16. Klaus Kinski
17. Gene Kelly
18. Peter Lorre
19. Charles Laughton
20. Max Linder
21. Groucho Marx / The Marx Brothers 
22. Tatsuya Nakadai
23. Ben Kingsley
24. Fredric March
25. Philippe Noiret
26. Bill Murray
27. Gary Oldman
28. Walter Matthau
29. Laurel and Hardy
30. Jean-Pierre Léaud
31. Yves Montand
32. James Mason
33. Tony Chiu Wai Leung
34. Steve McQueen
35. Boris Karloff
36. Dilip Kumar
37. Ian McKellen
38. Paul Muni
39. Jean Marais
40. Jerry Lewis
41. Liam Neeson
42. Lee Marvin
43. Nino Manfredi
44. David Niven
45. Bruce Lee
46. Aamir Khan
47. Christopher Lee
48. Edward Norton
49. Thomas Mitchell
50. Nanni Moretti
51. Karl Malden
52. Joel McCrea
53. Viggo Mortensen
54. Heath Ledger
55. Bela Lugosi
56. Joe Pesci
57. Harvey Keitel
58. John Malkovich
59. Joaquin Phoenix
60. Victor McLaglen
61. Armin Mueller-Stahl
62. Rudolf Klein-Rogge
63. Takeshi Kitano
64. Steve Martin
65. Martin Landau
66. Matthew McConaughey
67. Franco Nero
68. Robert Montgomery
69. Fred MacMurray
70. Kevin Kline
71. Nick Nolte
72. Jet Li
73. Ulrich Mühe
74. Masahiro Motoki

1. Laurence Olivier
2. Paul Newman
3. Toshiro Mifune
4. Jack Nicholson
5. Al Pacino
6. Buster Keaton
7. Jack Lemmon
8. Marcello Mastroianni
9. Gregory Peck
10. Peter O'Toole
11. Burt Lancaster
12. Robert Mitchum
13. Harold Lloyd
14. Michel Piccoli
15. Sean Penn
16. Klaus Kinski
17. Gene Kelly
18. Peter Lorre
19. Charles Laughton
20. Max Linder
21. Groucho Marx / The Marx Brothers
22. Ben Kingsley
23. Tatsuya Nakadai
24. Philippe Noiret
25. Bill Murray
26. Gary Oldman
27. Fredric March
28. Walter Matthau
29. Laurel and Hardy
30. Jean-Pierre Léaud
31. James Mason
32. Tony Chiu Wai Leung
33. Yves Montand
34. Steve McQueen
35. Ian McKellen
36. Boris Karloff
37. Dilip Kumar
38. Paul Muni
39. Jean Marais
40. Jerry Lewis
41. Liam Neeson
42. Lee Marvin
43. Nino Manfredi
44. David Niven
45. Edward Norton
46. Bruce Lee
47. Aamir Khan
48. Christopher Lee
49. Thomas Mitchell
50. Nanni Moretti
51. Karl Malden
52. Heath Ledger
53. Joel McCrea
54. Viggo Mortensen
55. Joe Pesci
56. Bela Lugosi
57. Harvey Keitel
58. John Malkovich
59. Joaquin Phoenix
60. Victor McLaglen
61. Armin Mueller-Stahl
62. Matthew McConaughey
63. Rudolf Klein-Rogge
64. Takeshi Kitano
65. Steve Martin
66. Martin Landau
67. Franco Nero
68. Robert Montgomery
69. Fred MacMurray
70. Kevin Kline
71. Nick Nolte
72. Jet Li
73. Ulrich Mühe
74. Masahiro Motoki

I still think the top 2-5 could be in any order, in my opinion. I don't know if Mifune is greater than Nicholson and Pacino.