The gorilla is a man in a gorilla suit. He first appears in the episode "I Had an Accident."
Role in series
"I Had an Accident"
He first appears disguised as Patrick, stuffs the real Patrick and Sandy into a bag, smacks them on the ground, and stomps on them, which makes SpongeBob finally go outside. He also hangs out with George and seems to be friends with him.
When SpongeBob asks what the gorilla is doing underwater in the first place, the gorilla panics and flees on George before they could question him any further, leaving everybody confused.
The gorilla appears in the live-action Patchy segments as his replacement at The Poop Deck. He is apparently a better cook than Patchy, but after the latter calls him "a smelly, hairy fleabag," the gorilla starts throwing food at Patchy.