She calls Timmy "Sport" because she forgets Timmy's name a lot.
Another thing revealed in the list of secrets is that she dyes her hair.
Her hair was originally going to be blue, but since Timmy's room was blue, it wouldn't have shown up, so it was changed to pink.
One of Wanda's eyebrows is always down, and the other is up.
Wanda's name was originally going to be Venus, to compliment Cosmo's "spacey" name. However, Butch Hartman went with Wanda because it seemed like a natural fit for her with her wand. She was also first designed frumpy and unattractive.
In "The Big Scoop", Chester and A.J. saw pictures and even mentioned Cosmo and Wanda but in Da Rules, it says if someone's fairies are mentioned or exposed by other people except fellow godchildren, the fairy or fairies go away forever. This may indicate they must first be revealed as fairies instead of just existent beings.
In "Wanda's Day Off", the other female fairies at a high-class beauty spa are disdainful of Wanda because she was wished there by her godson, instead of being rich and paying for it. Their disdain blossoms into jealousy when they learn that their crush Juandissimo, who works at the spa, still pines for her, which implies that Wanda is something of a beauty. Though she appears to have little social life (perhaps thanks to Cosmo), she has at least two friends as seen in "Dog's Day Afternoon".
In the series' early episodes (like the episode The Big Problem), Wanda's skin color was light pink instead of caucasian. It can be confirmed by seeing her along with Cosmo (who always had caucasian skin). The color of her skin was later changed to caucasian.
In Fairy Idol, Wanda calls the Timmy clone a "twerp", one of Vicky's well-known lines.
She, Cosmo, and Poof will always be Godparents of the same kid together, because they are from the same family.
Susan Blakeslee, who voices Wanda, who also voices over many female characters including Mrs. Turner and Anti-Wanda.
Cosmo and Wanda have been married for over ten thousand years.
Apparently she doesn't like watching violent things and prevents Poof from watching them (although she didn't mind CC Cruiser).
She doesn't speak Spanish although in the Jimmy Timmy Power Hour she called Jimmy 'Amigo' which is Spanish for friend. On the other hand, she might have learned some Spanish in between "Engine Blocked" and "Jimmy Timmy Power Hour".
According to Future Lost, she can put others to sleep just by talking to them this also affects herself if she says it to her reflection.
She is usually serious about everything but has been shown to have a very bad sense of humor according to the School's Out!: The Musical bloopers during the jail scene after Cosmo tries to do pull ups and than cuts the cheese she laughs at him and so does he. In Class Clown, she and Cosmo laugh at Timmy and don't take him seriously. In Hairicane, after seeing Timmy's bad hair cut she and Cosmo both laugh and so on.In conclusion, she can lighten up at times.
She's been calling Timmy sport throughout most of the series, but in an Oh Yeah! Cartoon short, Party of Three!, she called him slugger.
In the Season 9 episode, Let Sleeper Dogs Lie, she reveals why she calls Timmy sport, because fairies have bad memory and she always forgets his name.
She appeared in the Big Time Rush episode, Big Time Cartoon, only to have a line.
Even though she's smart, she can make dumb decisions. Like in Timmy's Secret Wish, she tried to poof up people to help Timmy but she choose Dark Laser which was a terrible idea and made it worse. In The Terrible Twosome, she tries to punish Poof even though she knows that Terrible Twos are a rebel stage and making Poof angrier.
She and Lois Griffin from Family Guy are very similar, in that they both always nag their husband and children (Peter, Cosmo , Meg , Timmy and Chris) and both have babies (Poof and Stewie)
Wanda, along with Cosmo, appeared in Ned's Declassified episode, "Daydreams".