Grandpa babysitting Timmy when he was an infant, is indirectly responsible for Timmy's buck teeth(due to Pappy letting him suck on a pacifier for too long).
Timmy has vomited 3 times in the episode "Squirrely Puffs"
Timmy is allergic to oranges and sauerkraut. It could be inheritable.
Timmy Turner has only gotten A's on his tests five times. When he got an A+ in the episode "Cosmo Con," his friends started screaming as they thought the world was coming to an end.
Timmy freaks out at seeing bare feet. In one episode, he got scared at a picture of his grandma's feet. It may have been where he developed his fear of feet, his grandma may have made him rub her feet.
His height is seen somewhat as 3 feet 7 inches, in the future, he's possibly 5 foot 6 inches
Timmy is afraid of clowns, according to "A Bad Case of Diary-Uh!". (Goof: In School's Out!: The Musical, Flappy Bob is dressed as a clown, but Timmy isn't scared. On the other hand, he may have conquered that fear sometime before or during School's Out: The Musical.)
Timmy is ambidextrous, but prefers to use his left hand.
Timmy has been eaten 12 times: twice by Vicky, twice by dinosaurs, twice by plants, once by a monster, once by Goddard, once by a shark, once by Mark Chang, once by the Loch Dimmsdale Monster, and once by a sand worm.
Timmy receives multiple wedgies from Francis and Vicky. When given a wedgie he wears briefs, but in No Substitute For Crazy! he and all of his friends' pants rip off revealing their boxers.
Some special abilities of Timmy include being able to use Wanda's voice, (in Hassle in the Castle and Mission: Responsible).
Timmy does therapy. This fact was revealed in "Mother Nature", and confirmed in "Take and Fake", when he says "I don't care what my therapist says ...". He has been going to therapy possibly since he was five, as seen in "Imaginary Gary" when he shows a picture of him (and Gary, from his imagination) in therapy.
He sees a therapist over his crush on Trixie Tang. Ironically, Tootie also sees her own therapist for the same reason: her crush on Timmy.
In the pilot episode, The Fairly Odd Parents!, his hair was dark red instead of its usual light brown. Beginning in Too Many Timmys!, his hair was light brown like it would be for the rest of the series.
In some episodes, whenever Tootie tries to kiss Timmy, he either runs away in fear or acquires help from his fairies. But on other episodes, he actually owns up to Tootie and has no problem kissing her. This suggests that Timmy is either scared of her (Usually because of Vicky or Tootie herself), doesn't want to hurt Tootie's feelings for him because of his crush on Trixie, or simply hides his feelings for Tootie because it's hard for him to decide whether it should be Trixie or Tootie, but mostly likes her as a friend.
During and after the episode Spellementary School, Timmy enjoys being babied by Cosmo and Wanda such as happily sucking on his pacifier.
Timmy's excuse for everything is that he got something on the internet. He even said he got heat vision on the internet. This excuse did not work in Inspection Detection as Timmy's parents found out that they don't have internet.
As seen in the episode Hairicane Timmy's hair in the end is bald but in the next episode his hair is back. However Timmy may have just simply wished that his hair was back since anything damaged on him is usually repaired by his godparents.
Timmy's full name refers to several people. Timothy comes from creator Butch Hartman's brother, Tiberius comes from James T Kirk from Star Trek, and Turner may be a tribute to media mogul Ted Turner who controlled Hanna-Barbera Studios which Hartman worked for.
Timmy has shown many symptoms of Attention Deficit Hyperactivity Disorder (ADHD). These include: Major focusing problems (even admitted a few times in the series), hyperactivity (not counting his sugar rush in Just Desserts!), antisocial behavior (he only has two friends, not including his "back up friends"), forgets what he is doing occasionally, and even goes to therapy (usually having to deal with social problems). He is also great at finding things, and brain scans and studies of ADHD show that those who have it show more "hunter-gatherer" traits.
In Super Brawl 2, Timmy is shown in his Cleft costume but instead of having his trademark pink hat, he has a red hat.