Timmy has the same hairstyle as Cosmo, Vicky (other than the ponytail) and Danny Fenton from Danny Phantom.
In the original concept, Timmy's hat was intended to be blue, but because Butch Hartman's blue marker had run out of ink, Timmy's hat became pink instead.
Timmy has his own theme song.
Timmy's full name is Timothy Tiberius Turner.
Timmy is named after Butch Hartman's younger brother, Timmy Hartman.
Timmy's birthday is March 21, which makes him an Aries in the horoscope.
Timmy's hair was originally intended to be red, but his hair color was dyed so it wouldn't match Vicky's.
Timmy can burp the alphabet.
Timmy bites his toenails, which is strange, because he is horrified by bare feet.
When having nightmares, Timmy grinds his teeth.
His trademark pink hat is due to his parents expecting a girl. 
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 in The Good Old Days!).
Timmy has vomited 3 times in "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 "Cosmo Con," his friends started screaming as they thought the world was coming to an end (he got an A+ due to his short attention span and him doodling).
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.
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.
Timmy does therapy.  He has been going to therapy possibly since he was five because there is a picture of him (and Gary, from his imagination) in therapy.
He sees a therapist over his crush on Trixie Tang. 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 in Father Time!. This excuse did not work in Inspection Detection as Timmy's parents found out that they don't have internet.
In the original transcript of "Just the Two of Us!", Trixie discovers Timmy's fairies and nearly causes him to lose them, but he had managed to unwish everything moments before her discovery.
When the Oh Yeah! Cartoons shorts are reused in later episodes, Timmy's voice is redubbed using his current voice actress (Tara Strong); this may be to due to continuity, since Strong's voice sounds a bit different than Bergman's.
As seen in 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.
He appeared in the Big Time Rush episode, Big Time Cartoon.
According to Cosmo, Timmy Turner weighs 50 lbs. without his buck teeth, but 77 Secrets of The Fairly OddParents Revealed! shows that Timmy weighs 60 lbs. with his buck teeth. So, that means Timmy's buck teeth weigh 10 lbs. In the Oh Yeah! Cartoons short "Too Many Timmys!, Timmy says that he's 45 lbs., all muscle
According to It's A Wishful Life, Timmy's presents make the world worse not better. However due to the fact that Jorgen Von Strangle arranged the event as a test, it's not fully clear if this is true.
In Abra-Catastrophe! Timmy is shown when he was young not having fully-formed buck teeth, but in every episode to feature Timmy as a baby (not including The "Good Old Days!", Although it does explain him getting his buck teeth), he has his buck teeth.