|First appearance:||"Muscle Woman"|
|Latest appearance:||"Ace Balthazar Lives"|
Sir Gabrlthorp is a character who appears in "Muscle Woman". He apparently built "castles" out of moldy and dirty mattresses in the creek bed in The Park. It was Mordecai and Rigby's job to get rid of him (originally Muscle Man's job). Later, when Starla was destroying The Park, Gibelthorp stepped out and opened up a teleportation hole, and headed back to a place that seemed to have a real castle, so it seems he actually was a real knight from the past, but somehow is in the present.
He appeared again in "Ace Balthazar Lives", where he was believed to be Ace Balthazar by Mordecai and Rigby. They then tried to remodel his appearance and personality to be more like Ace and eventually succeeded and even got him to perform a concert. However the ghost of the real Ace Balthazar appeared and showed his disapproval of the faker, but after Sir Gabelthorp proved his crashing prowess, Ace approved him and let him perform, however he could only play lute music so he was booed off the stage, and the ghost performed instead. Sir Gabelthorp then enjoyed Ace's music so much that he used his magic ring to open a portal to his home, Kingdonia and summoned his fellow knights and the Eggscellent Knight to party with him at the concert.
He wears a burlap-made potato sack as a shirt. It is held together by a string and you can see his underpants. He wears socks, but no shoes. He has a cardboard sword and armor, and he wears a cardboard "helmet" that says Oats on it. He also has mismatched socks on him. (The left sock is red and the right sock is blue.)