Lil' Mac is Mr. Gus' nephew and has a violent nature when he's not around him as seen in the episode Lil' Mac. He is voiced by Grey DeLisle.
Lil' Mac looks like a child version of Mr. Gus, he's short with a big round head and green skin, he has green dinosaur scales that act like hair, he has pink lips with one tooth showing, yellow eyes and two nostrils. He normally wears a blue shirt and just like his Uncle Mr. Gus, he doesn't wear any pants.
When Lil' Mac is around Mr. Gus, he tries to act like an innocent little angel that Mr. Gus just adores, he cool with Mr. Gus as they like to fist bump each other. When he's not around Mr. Gus, he tends to act like a devil and he has a very destructive nature as he broke the TV and Uncle Grandpa's favorite toy, he was questioned if he ever had any sense of morality, he will often cry as he is a little kid. He does show a bright side when he wanted to play with Uncle Grandpa and Pizza Steve at the end of the episode.
Lil' Mac's has the same name of the "Punch Out" character Little Mac.