|Relatives|| Father: Terrence |
|First Appearance||"The Day the Earth Stood Cool"|
|Voiced By||Patton Oswalt|
T-Rex or Tyrannosaurus, is the child in a cool family.
Bart and Lisa met him when they were invited into 740 Evergreen Terrace. They were surprised to see all the obscure things that T-Rex had in his room and were even more shocked to find that he didn't own a TV. Bart, Lisa and T-Rex quickly became friends and he probably has a thing for lisa.
At T-Rex's birthday party, T-Rex mocked the present that Homer had made for him, and mocked Homer. Bart stood up for his father and attacked T-Rex, leading into a fight. This fight is what made the two families stop being friends.
Later, after Bart and T-Rex had forgiven each other, Bart asked T-Rex if he wanted to come to his to watch The Krusty the Clown Show. T-Rex said that he had to stir compost but Bart persuaded him to leave it. The compost started to burn and set fire to the Devil Donuts truck. After this, T-Rex and his family left Springfield.
T-Rex seems to be nasty around his friends, as seen when he mocked Homer. However, he doesn't seem to hold grudged for long and knows when he is in the wrong and accepts it.
T-Rex is shown to be a supporter of English football club West Ham United as there are banners of the team in his bedroom.
It is also possible that T-Rex is left-handed judging by the bass guitar neck behind him in one scene