Leo, Len, Lennie (or Lenny).
Famous people named Leonard:
Singer Leonard Cohen; composer Leonard Bernstein; actor Leonard Nimoy; singer Leonard "Lenny" Kravitz; football players Leonard Hankerson, Leonard Johnson, and Leonard Pope.
Feel like watching The Secret Life of Pets over and over? Hope so, because that's what you'll do when your little Leonard insists on it because there's a poodle with his name.