The Tyrannosaurus rex or T. rex for short, is a character that makes a cameo at the end of the episode "Ugh," as a "gift" for Patchy which was given by Potty which he starts to chase Patchy. He also makes a cameo in "Truth or Square" at the beginning with the other clips of Patchy.
He is a large T. rex with dark green color on the top of his body and olive green on the bottom. His animation moves are very similar to the Bumbles' moves in the Rudolph TV special.
He first appears at the end of "Ugh" as a "gift" for Patchy which was given by Potty. He chases after a scared Patchy before catching him and beginning to eat him as Patchy ended the episode screaming in pain.
He later appears in "Truth or Square" where the clip of the T. rex chewing on Patchy is shown.
In full body view when he was shown to Patchy from Potty and when Patchy gets chased by him, his animation movements are done in stop-motion.
In close-up view when he was devouring Patchy from the legs, he was a hand puppet which looks exactly like his head.