Humphrey bogart was in movies such as the Maltese falcon, Black legion, Marked Woman, Dead end and many other movies. He had a great relation ship with Warner Bros studios and was often picked for movies due to his gentlemanly behaviour and his professional and cool nature.
Ingrid Bergman has appeared in movies such as Adam has four sons, Rage in heaven, Dr Jekyll and Mr Hyde. At the time when Casablanca was released she had a pretty good relationship with Hollywood, however in 1950 she left Hollywood due to an affair with Rossellini which led to US politicians throwing her out of the country.
Paul Henroid had appeared in movies like For Men Only, Live fast Die young and Girls on the loose. He had a decent relationship with Hollywood until he was blacklisted by the five major studious for five years and he never understood why.
Conrad Veidt was a German born actor who escaped Germany to become an actor in America. The directors of the movie chose him to play the role of a German officer as he can create an authentic character to play the role. He often plays villains such as his role in The Man Who Laughs. He had a good relationship with Hollywood and was famous before Casablanca and I think he was cast for the movie due to his recognition from the audience.
Peter Lorre was very famous before Casablanca and starred in a lot of horror movies. He was cast for these kind of roles due to looking undesirable which is shown in his role in Casablanca where he plays a supportive character who doesn’t contribute much to the movie. Movies he appeared in was M, The Maltese falcon, The man who knew too much and Mad Love.
Dooley Wilson Appeared in a few movies before Casablanca such as Cairo and Take a letter Darling. He was chosen for his role in Casablanca due to upbeat and happy nature which fits his role as Sam in the movie. He gained more notoriety after the release of Casablanca and starred in a lot of movies.