Groucho Marx was a comedian who played the гитара and sang. His name was Julius. He was called Groucho for two reasons: 1): The grouch-bag underneath his collar, and 2): because of his character often being grouchy. He was born in 1890.
Harpo Marx played the harp and didn't talk because he forgot his lines. However, this ended up well, because he got to do the whole thing in pantomime. His name was Adolph and changed it to Arthur in 1911. He was called Harpo because he played the harp.
Chico Marx was an Italian American, and he played the piano. His name was Leonard. He was called Chico, because...