He's probably best known for his two movies with Mel Brooks, The Producers, where he played the Nazi playwright, Franz Liebkind and as Inspector Kemp in Young Frankenstein.
From What's Up Doc to Fernwood Tonight, Kenneth Mars was equally memorable in almost every role he played. And although he rarely got the chance to do drama, he showed that he had the talent to be serious as well, as is evident in the 1971 drama, Desperate Characters with Shirley MacLaine.
They don't make actors like Kenneth Mars anymore. He brought such a goofy madness to his characters and still managed to deliver more than a one note performance, which can't be said for a lot of the comic talent of today. He is no longer with us and comedy just doesn't seem the same.