Rex loves to have fun. He is the most energetic of the siblings. He is not very smart, but luck has sympathy and makes Rex win most of the time due to pure luck. When he is with Utah, Utah usually has to keep Rex out of trouble. If Rex was to be compared to a drink, he says he would be coffee due to it's high content in caffeine.
Rex has a green body with white fingernails and light turquoise patches on the insides of his hands. He has dark geen feet and also has a fang on the right-hand side of his mouth.
Rex seems to think that Orange Kirby is weak and pathetic. Orange Kirby does not take kindly to this.
- He is based off of T-rex from Dinosaur Comics.
- He lives with his siblings in Orange County in Florida.