Ah, Margaret Dumont. The straightest of all the straight women. She worked as a foil for the Marx Brothers (of course), and also Danny Kaye, Laurel and Hardy, and W.C. Fields, among others.
I have always loved her, probably because I myself enjoy playing this type of character. I always thought I'd be a good Margaret Dumont type.
Of course, she was best known for her films with The Marx Brothers, and her deadpan interactions with Groucho. The myth about her was that she didn't realize her films were actually comedies, and never got the humor in them. In this clip, an elderly Groucho Marx addresses and continues to confirm that idea (and other things, including, poignantly, how he just doesn't get the phenomenon of the musical Hair):
I don't believe it for a second. It's interesting that this perception of her is still commonly held, but I think we can give her a little bit more credit, right? I mean, come on, she was born in Brooklyn, her real name Daisy Baker and was widowed by the time she was 35. She was no spring chicken when she worked with the Marx Brothers, and I think she very craftily manufactured the persona that served her quite well throughout her career, myths and all. It takes a lot of skill to be a straight man - and even more especially a straight woman. There's no way she didn't know what she was doing - and doing so well.
Indeed, she herself shattered the myth of Dumont the humorless dowager. From Groucho: The Life and Times of Julius Henry Marx by Stefan Kanfer:
[T]he image of a society-woman-turned-actress, wholly unaffected by the mishegaas around her, appears to have been the richest jest of all, Dumont's ultimate joke on Groucho and company . . . Out of Groucho's hearing she gave an accurate self-description--"I'm not a stooge. I'm the best straight woman in Hollywood"--and made a very keen analysis of what she did for a living: "There's an art to playing straight. You must build up your man but never top him, never steal the laughs from him."
She was a perfect foil to the brilliantly chaotic Marx Brothers, and did her part masterfully. I'm not sure, come to think of it, that I could suppress my ego enough to play it that straight. I think I'd be too tempted to get a pratfall in there for myself. So, let's give her the credit she is due as an actress and comedienne - and doubt no longer that she knew exactly what she was doing. Margaret Dumont, straight woman extraordinaire, we salute you!