It is responsible for the creation of The Fairly OddParents and many other cartoon shorts that would end up becoming part of Nickelodeon's main line-up such as ChalkZone and My Life as a Teenage Robot. The first episode of The Fairly OddParents was aired in the eighth episode of the show. The next two seasons of that show featured nine more of The Fairly OddParents shorts.
The Fairly OddParents shorts from Oh Yeah! Cartoons, which are sometimes referred to as Season 0, feature the main characters Timmy Turner, Cosmo, Wanda, and Vicky. The shorts also introduced Jorgen Von Strangle, Tootie, and the Tooth Fairy, the latter two of which had alternate designs to their later FOP series counterparts. Timmy's parents were also featured in these shorts, although only their legs and pants are viewed most of the time and their faces were never shown on-screen, similar to the appearances of the titular heroes' parents on Cartoon Network's animated series Cow and Chicken; they were given full character designs in the main half-hour series.
Around the same year the third season of Oh Yeah! Cartoons ended, The Fairly OddParents was picked up as an actual Nickelodeon series. It became by far and wide the biggest spin-off in terms of length and popularity. May Kay Bergmen was originally going to voice Timmy. She did between 1998-1999. However, in November 1999, she died by a shooting herself with a gun. Wikia's Mary Kay Bergmen article will explain more about her death. So, episode 6, "The Temp" was the last episode to air during her lifetime. But, in episode 7, "The Zappys" she finished all her lines in time. So we hear her voice one last time before Tara Strong fills in for episodes 8-10 and the TV series. If Bergmen wasn't foolish enough to shoot herself, she would have been voicing Timmy in episodes 8, 9, 10, and the TV series.