List of characters

Main characters
These characters have all had a major role in the story of the show. Most, if not all of them, have appeared in the majority of series.

Other major characters
These characters play a major role in the story, often times having more than one or two episodes that focus entirely on them, but are not always guaranteed to appear.

Supporting characters
These are recurring characters that have appeared in more than one episode, but rarely do they ever have any major effect on the plot, and typically serve as background/group shot fodder.

One time characters
These are characters that have only appeared in one episodes, but were important characters in their lone appearance. Some of them have also appeared in other episodes in background shots.

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Minor characters
These are characters that have only appeared in a few episodes, usually as bit characters, and have little effect on the story.

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Alternate forms
Several alternate forms have appeared of the characters, usually as a direct result of wishing.

Crash Nebula
These are one-time characters that appeared in the show-within-a-show spin-off, "Crash Nebula", which was broadcast as part of Season 5. However, the spin-off was never picked up as a series by Nickelodeon, and none of these characters have appeared since.

Live action
The tenth year anniversary special "A Fairly Odd Movie: Grow Up, Timmy Turner!" are played by live action characters. Thirteen years have passed since the main series, and everyone but Timmy Turner has grown up.