Question: What nationality was the actor who played Jules in Jules and Jim?

Context articles: François Truffaut
Oskar Werner
James Gaines
Carson Beckett
The Burglar and the Lady
Jules and Jim
Abel Tarride
Chris Demetral
Michael Gambon
Henri Serre

François Roland Truffaut (] ; 6 February 1932 – 21 October 1984) was a French film director, screenwriter, producer, actor, and film critic, as well as one of the founders of the French New Wave.
 In a film career lasting over a quarter of a century, he remains an icon of the French film industry, having worked on over 25 films.
 Truffaut's film "The 400 Blows" came to be a defining film of the French New Wave movement.
 Unique in world cinema, the movie is followed over 20 years with classics "Stolen Kisses", "Bed and Board" and "Love on the Run" between 1958 and 1979.
 He also directed such other classics as "Shoot the Piano Player" (1960), "Jules et Jim" (1961), "The Wild Child" (1970), "Two English Girls" (1971), "Day for Night" (1973) and "The Woman Next Door" (1981).
Oskar Werner (13 November 1922 23 October 1984) was an Austrian stage and cinema actor whose prominent roles include two 1965 films, "The Spy Who Came in from the Cold" and "Ship of Fools".
 Other notable films include "Decision Before Dawn" (1951), "Jules and Jim" (1962), "Fahrenheit 451" (1966), "The Shoes of the Fisherman" (1968) and "Voyage of the Damned" (1976).
James Gaines, birth name James Larry M. Gaines Jr., is an African-American-Filipino character actor, writer and director with dual nationality, born on May 18, 1955, in Maui, Hawaii.
 He was sometimes also credited as Jaimes Gaines, Jim Gaines, and James Gainers.
Dr. Carson Beckett is a fictional Scottish character in the Canadian-American science fiction television series "Stargate Atlantis", a spin-off series of "Stargate SG-1".
 He is portrayed by Scottish-born Canadian actor Paul McGillion, who previously played Dr. Ernest Littlefield in the first season of "SG-1".
 The character's Scottish nationality was only decided after McGillion's audition.
The Burglar and the Lady is a play written by Langdon McCormick.
 Like many of McCormick's plays, it was primarily a touring show and first premiered on October 1, 1905, at the State Street Theatre in Trenton, New Jersey.
 It came to Broadway in September 1906, appearing for a week at the American Theatre.
 The story pitted Sherlock Holmes, the famous fictional detective created by Arthur Conan Doyle, against A. J. Raffles, a fictional criminal created by E. W. Hornung.
 McCormick did not bother to ask permission for the use of either character.
 Former boxer "Gentleman Jim" Corbett played Raffles.
 The character's nationality was changed from English to American to match Corbett's casting.
 It was adapted as a movie in 1914, with Corbett again playing Raffles, although the adaptation removed the Holmes character.
Jules and Jim (French: "Jules et Jim" , ] ) is a 1962 French romantic drama film, directed, produced and written by François Truffaut.
 Set around the time of World War I, it describes a tragic love triangle involving French Bohemian Jim (Henri Serre), his shy Austrian friend Jules (Oskar Werner), and Jules's girlfriend and later wife Catherine (Jeanne Moreau).
Abel Tarride (1865–1951) was a French actor.
 He was the father of the actor Jacques Tarride and the director Jean Tarride.
 He played the role of Jules Maigret in the 1932 film "The Yellow Dog", directed by his son.
Christopher Peter "Chris" Demetral (born November 14, 1976) is a former American actor best known as Jeremy Tupper, the son of newly divorced New York book editor Martin Tupper (played by Brian Benben) on the HBO series "Dream On".
 He also played the title character in the short-lived series, "The Secret Adventures of Jules Verne" on the Sci Fi Channel.
 He also played Christopher Ewing in "".
Sir Michael John Gambon {'1': ", '2': ", '3': ", '4': "} (born 19 October 1940) is an Irish-born English actor who has worked in theatre, television and film.
 Gambon has played the eponymous mystery writer protagonist in the BBC television serial "The Singing Detective", Jules Maigret in the 1990s ITV serial "Maigret", and Professor Albus Dumbledore in the final six "Harry Potter" films after the death of previous actor Richard Harris.
 He has won four BAFTA TV Awards and three Olivier Awards.
Henri Serre (born 26 February 1931) is a French actor who is best known as Jim, a "vivid, melancholy, and finally tragic figure" in François Truffaut's "Jules and Jim".
 Other appearances include "The Fire Within", "Section spéciale" and "Mister Frost".