Cosmo Cosma and Wanda Venus Fairywinkle Cosma are the married pair of fairy parents that are assigned to Timmy Turner. They are more like the smarter, caring parents Timmy never had. To keep themselves a secret, they usually masquerade as Timmy's pet goldfish and live in a magical castle inside of his fishbowl. Timmy is forbidden from revealing their existence, for the penalty is losing them for good. In the beginning Season 6, they had the first fairy baby in over 10,000 years, whom Timmy names Poof. It is also revealed in one episode that Cosmo is directly responsible for many historical tragedies, such as the volcanic eruption that destroyed the city of Pompeii, Italy and the sinking of Atlantis. He also destroyed Pluto in one episode. However, Wanda is responsible for the extinction of the dinosaurs, as revealed in the episode "Cosmo Con." In "Fairly Odd Baby", Cosmo and Wanda have a baby, Poof, but it is Cosmo that gets gives birth, apparently a natural even in Fairies.

Poof Fairywinkle Cosma is Cosmo and Wanda's only natural child, and Timmy's little fairy brother. He was the first fairy baby born in over 10,000 years; the last one was Cosmo, who caused so much damage, that after he was born, the Supreme Fairy Council forbade any more fairy babies to prevent anything like him from ever being born again. Poof is possibly much smarter than Cosmo. His untapped magical powers are channeled through a magical rattle that acts like a normal wand. Without it, Poof's hiccups cause natural disasters, his laughter causes good things to happen, crying causes bad things to happen, his burps cause the person holding him to get struck by lightning and his flatulence seem to have the ability to warp reality and completely blow away problems. His name was given to him by Timmy because "Poof" is the only word he says. Poof is shown to have a close fondness of Timmy as his name is the first word he says other than his own name (the episode "Mission Responsible" when aboard Dark Laser's ship). In Wishology, Poof becomes a Ninja after watching part of a movie based on Timmy's victory against the Darkness in Part 1 and throughout the show beats up someone using Ninja moves (usually Cosmo or Wanda ). It's unknown if Poof still has these moves after the special, but they are extremely useful as Poof took down an entire gang of Eliminators after escaping the prison cell. Poof was also seen without his rattle during moments of the special, but his crying and other emotions caused nothing to happen (unlike what happened in Fairly Odd Baby), which probably means that he hid his rattle.

Strangely, Poof is shaped like a ball when he was born, yet Cosmo's birth in Fairly Odd Baby had him shaped more like a human. Also, Poof is a new super sidekick puppy to Timmy, as Cleft, when he visited the Crimson Chin in "CHINdred Spirits". It has been confirmed that there is now a new character called Foop (aka Anti-Poof), and unlike Poof who is shaped as a ball when he was born, Foop is a cube.