The Baby Man is an adult baby and prisoner in Mr. Pickles' lair. He makes his debut in Tommy's Big Joband has made some appearance since then.
The Baby Man was present at Mr. Pickles' fetish party where the dog proceeded to kill and dismember most of the party-goers with a chainsaw. He then took the body pieces and surgically fused them with the Baby Man. Despite this, the Baby Man retained his playful attitude and will often be found aggressively demanding milk.
The Baby Man is seen again when Grandpa inflitrates the lair and is attacked by the Baby Man. Grandpa is then saved by a robot duplicate of the Sheriff shoots the Baby Man, injuring him non-fatally.