Levi's not your buddy this time, but we'll answer this anyway.
-Anything related to Levi (Levite, Leviticus, Leviathon, etc.)
-Little Man, Little Bit, Bitty Boo, Boo, Bittles
-Monkey and/or Monkey Man, or Monks
-Hairy (or occasionally, Saggy Britches)
-Red
-Yorkie/Yorkster
Other than Levi, he's most commonly called Red...because his facial hair is strawberry blonde.
This many nicknames cannot be normal.