No tribute to comic character actors could be complete without mention of the great Margaret Dumont. She was, without question, The Greatest Straight Woman of All Time. Marx authorities ranging from Dick Cavett to Groucho himself all say Dumont didn't get the jokes, on or off screen, but the Siren doesn't buy it. Dumont had a long career as a comic foil, and face it, she is too good not to know what she's doing. To be a good straight (wo)man, it isn't enough to keep a poker face and ignore the lunacy. Kitty Carlisle, Lillian Roth and Kay Francis all do that, and they still get flattened. No, Dumont had something extra--the ability to broaden her characterization with each new joke. Her finest moments probably came in Duck Soup, where her manner is so impeccably grand she seems to have wandered in from some Ruritanian operetta filming on another soundstage. Groucho was one of the funniest men American comedy ever produced--and if you want to say THE funniest the Siren won't argue. But it takes nothing away from Groucho to state that he was never funnier than when he was bouncing joke after joke off Dumont's imposing figure.
I'd have to say that strikes me as exactly right. Because of typecasting, audiences could leave when the lights came up thinking that Dumont had no sense of humor. That's a shame, because it almost certainly isn't true. Being a straight man or straight woman is a skill, one that tends to be invisible to the audience. Bud Abbott, with a few exceptions, didn't say anything funny either. And yet it's hard to think of Costello working as well with anyone else.
Dumont was in the whole first run of Marx Brothers movies, only excepting the two postwar comedies they made. Groucho had many of his best scenes opposite her. Based on the evidence, she got their humor as well as anyone whose last name wasn't "Marx."