Movies of the 1930s and 1940s often featured black actors in secondary comic-relief roles, frequently playing racial stereotypes. I recently suffered through an extreme example of that in Charlie Chan in Egypt (1935, reviewed here), which is a pretty bad movie all around, but sinks into the depths with its treatment of Stepin Fetchit, whose real name was Lincoln Theodore Monroe Andrew Perry. Perry made a career of playing an offensively stereotypical character often described as "the laziest man in the world," but in his defense, his Stepin Fetchit character enabled him to become a major character actor and a millionaire and to receive star billing in film credits and advertising. His performance has sometimes been described as "subversive." At the same time he was playing in Stepin Fetchit roles on the screen, Perry had a second career as a writer, notably for The Chicago Defender, an important African-American weekly newspaper. One of his friends was Will Rogers.
I don't know that Perry was ever handed a worse role than in Charlie Chan in Egypt, where his character at one point says he had been "won" by his current employer in a card game. Said employer, who's incredibly enough supposed to be a good guy, treats Fetchit like an abused animal, for example striking him for moving too slowly or hesitantly when forced to go first into a dangerous situation. On the other hand, since Perry's character is also presented as likable, it's possible he thought the scenes in question would disturb at least some white audience members and perhaps prompt some negative thoughts about racist mistreatment.
Later pictures in the series featured Mantan Moreland, another black comic actor, in a vaguely similar role as Chan's chauffeur, Birmingham Brown. Moreland was regularly required to act comically scared and roll his eyes, but at least he was able to play more of an everyman character not necessarily worse than the comic sidekicks played by white actors. Two of the Chan movies, The Scarlet Clue (1945) and Dark Alibi (1946) featured a famous Vaudeville routine called "Incomplete Sentences" involving Moreland and his longtime Vaudeville straight man Ben Carter. Carter had his own film career that included roles in such well-known films as A Day at the Races (1937) with the Marx Brothers and the Harvey Girls (1946) with Judy Garland.
The YouTube clip below excerpts the "Incomplete Sentences" scenes from those two Chan movies, and while they're yet marred by some unfortunate elements of racial stereotyping, the routine itself is reasonably funny, with Benson Fong (as Charlie Chan's son) and Sidney Toler (Chan) getting into the act as well.
(Having a white guy play a Chinese-American detective is a whole other subject that I won't go into for now. At least the Asian characters weren't subject to the same negative portrayal African-Americans endured.)
Finally, I apologize if anyone is offended by my posting the clip. As I said, it has its offensive aspects, but I think the positives outweigh the negatives, and Moreland and Carter deserve to be remembered as gifted comedians and comic actors. (Carter was also an excellent singer.)