More elusive than the famed "fifth Beatle," Milton "Gummo" Marx somehow managed to avoid the spotlight that shone so brightly on his four brothers yet was perfectly content that it was so, an attitude so decidedly un-American it's a wonder Joe McCarthy didn't go after him instead of the Communists. Always uncomfortable on stage, Gummo left the act when he was drafted shortly before the Armistice in 1918. After the war, he worked as a theatrical agent, representing among others his brother Groucho.
That's Gummo on the bottom of the pile there.
He earned his nickname either because he frequently wore rubber overshoes (a.k.a. galoshes or gumshoes) or because he crept up on people as quietly as a "gumshoe" (detective). I've read both theories.
In honor of his birthday today (he was born in 1892), here's the famous "elephant in my pajamas" scene from 1930's Animal Crackers. Admittedly, this has nothing to do with Gummo, but any excuse in a storm, right?