Mr. Muscul is a minor character who makes several cameo appearances throughout the series, first appearing in the episode "Shanghaied."
He is an olive-green fish who has a big, muscular figure with tattoos dotted all around his body. He has orange hair made into "spikes" and he wears headphones.
He is rather rude and physically aggressive, as he is not afraid to beat people up should they mess with him. Sometimes he will even exhibit violence towards others for no reason or for the entertainment of the kids.
Despite this, he is shown to have a nice side, as he happily gave Patrick a high-five and attended SpongeBob's birthday party, wishing the latter a happy birthday.
Role in series
Mr. Muscul appears as a cameo, walking down the street while the Flying Dutchman is trying to find fish to scare.
He appears in this episode as a customer in the Krusty Krab. When Squidward tries to give him his order, SpongeBob makes him spill the food on the tough guy's face. Mr. Muscul then punches Squidward in the face for the incident.
He speaks for the first time. Squidward gives Patty to Mr. Muscul, but SpongeBob does not want her to be eaten and saves her by replacing the patty with his shoe. The tough fish says he loves grilled shoe and happily eats it.