Mac, Bloo, their friends, and everyone at Fosters despise Terrence and enjoy whatever misfortune befalls him, knowing full well he deserves it.
He has a mullet haircut, a bad case of acne on his face and wears a grunge style of plaid wool shirt, a black t-shirt underneath, blue-grey jeans and white sneakers.
Terrence enjoys constantly bullying his younger brother Mac and trying to make his life miserable. The one thing he hates more than anything else is when Mac spends time with his best friend Bloo, and his biggest wish is for Mac and Bloo to never see each other again. In spite of his bullying attitude, he was seen watching a soap opera (The Loved and the Loveless) in "Berry Scary." He is also incredibly stupid, (though nonetheless he is not as stupid as Cheese and unlike him does have some moments of intelligence) which makes him very easily outsmarted.
In the pilot, he conspires with Duchess to get rid of Bloo permanently, but fails and is punished by being locked in the imaginary horse stables, where he is attacked by the unicorns, whom he had called "girly" earlier in the episode.
In Berry Scary, he is seen watching the soap opera, The Loved and the Loveless. When Mac returns home, he changes the channel claiming he was channel stuck as he's embarrassed about his brother seeing he likes the show.
In Seeing Red, Terrence creates an imaginary friend named Red to bully Bloo so he can bully Mac uninterrupted. But Red ends up making friends with Bloo instead. Enraged at this, Terrence berates him, only to have Red turn on him and toss him away, making him suffer every punishment Red went through.
In Beat with a Schtick, Mac and Bloo make a deal with him that if he beats up the New Guy, he'll get to bully Mac without being told on. Terrence gladly accepts, only to fail and come running back shortly afterwards, screaming in terror.
In Eddie Monster, he wants to be part of the Extremeasaur Battle circuit but is kept out because he doesn't have an imaginary friend. While complaining, he meets Eduardo in a dumpster in the slums of the city and recruits him to fight in the contest. Surprisingly the cowardly friend does well and Terrence manipulates his new confidence to advance further. While they are in the finals, he is caught when he brags to Mac about it and is later disqualified from the circuit. As an act of revenge, he locks Mac, Bloo, Wilt and Coco up with a Pikachu-like Extremeasaur. However, Eduardo manages to rescue them. Outraged at this, Terrence asks how he did it without panicking. While he says it, he calls him a "scaredy baby," making Eduardo angrily exclaim that he's no scaredy baby. Terrence is then knocked in the Extremeasaur's cage and gets shocked. He gets so scared that he wets his pants, running away in humiliation afterwards.
In Duchess of Wails, Terrence tells Mac that because their mother cannot stand Duchess, whom their next-door neighbors, the Applebees, have adopted, she plans to have their family move to Singapore, which Terrence mistakenly believes to be in Wisconsin. He even gets everyone at Foster's to help him keep Mac and Bloo from getting Duchess back into Foster's, but fails when they learn about Mac moving and agree to take her back.
In A Lost Claus, he, Mac and their mom all celebrate Christmas together. After Mac opens his last present, being a pair of toy guns that shoot ping pong balls, Terrence shoots at him with one of them until he leaves. After which he shoots their mom, apologizing shortly after doing so.
Terrence also appears in Infernal Slumber where he attempts to wake up his and Mac's mother to show her Mac's friends being at their apartment, get Mac into trouble and have him never see his friends again, but Cheese jumps on and covers his face to keep him quiet and Eduardo ultimately knocks him out. And when Terrence explains to his and Mac's mom about Mac's friends being over and that Mac never gave Bloo up, she doesn't believe him and grounds him.
Terrence is seen in two flashbacks in I Only Have Surprise for You, where he, his and Mac's mom, Bloo, a bunch of kids and a dog humiliate Mac in a surprise party.
In The Buck Swaps Here, Mac mentions him when he points at a moustache and the words, "Ha Ha!" on the packaging of one of his collectable Rocket Wars toys, claiming that Terrence drew it, only to have Bloo reveal that he did it himself out of boredom.
Mac mentions Terrence in Fools and Regulations when he explains that he let him borrow his video games for a day in exchange for never telling their mom he started a fire in their apartment (which, coincidentally, is something Bloo did earlier in the episode).
Terrence returns for a cameo appearance (and his final appearance) in the series finale, Goodbye to Bloo, where he and Mac are seen moving boxes outside their old apartment. Terrence angrily tells Mac that a box of his belongings is blocking his path. Mac volunteers to carry it as it has fragile things inside. Upon learning this, Terrence purposely drops it, breaking its contents to make Mac angry.
- House of Bloo's
- Berry Scary
- Seeing Red
- Beat With a Schtick
- Eddie Monster
- Duchess of Wails
- A Lost Claus
- Infernal Slumber
- I Only Have Surprise for You (flashbacks)
- Goodbye To Bloo (cameo)
- He sounds like Kevin from Ed, Edd 'n Eddy, as they both are voiced by females using a deep voice.
- Tara Strong once said in an interview with voice actor Rob Paulsen that Terrence is her least favorite role she's done because it strained her vocal chords.
- Starting in Beat With a Schtick, he appears with a different mullet haircut.
- Terrence makes most of his appearances in Seasons 1 and 3. He only has one appearance in Seasons 2 and 6, is seen in only 2 episodes in Season 4 and doesn't appear at all during Season 5.
- Terrence's golden trading card statistics from the Foster's Home for Imaginary Friends Leapster game include:
- Likes watching soap operas.
- Likes pizza.
- Dislikes anything girly.
- Dislikes ALL Imaginary Friends.
- Terrence's name is misspelled as "Terrance" in the game.
- Despite what his card says, he did create an imaginary friend of his own in one episode in spite of his hatred for them. He is also shown to like Extremasauruses.