SpongeBob SquarePants (voiced by Tom Kenny) is a undersea fry cook-turned world class adventurer who first meets Aang, Katara, Sokka and the others while stranded in Alice Springs, Australia.
SpongeBob is a very clueless, immature, and hyperactive character with a happy-go-lucky personality and a heart of gold. He is an extremely determined person, and will often stop at nothing to accomplish a task, especially if its concerns his friends. He is also somewhat dramatic to the people who are kind to him, for example, to the mailfish. He is also very over-confident and tends to make a big deal of small problems, such as losing his name tag.
- SpongeBob has been shown to have no knowledge of human medical conditions as seen in his first encounter with Team Avatar when Eliza's appendix burst.
- When the Fire Nation threatened to burn the ATA Sky Base, SpongeBob showed off his aerial skills upon racing to the scene.
- SpongeBob has encountered the Crystal Gems Ruby and Sapphire in the past, as mentioned in "Countdown to Vestroya".
- SpongeBob uses his fry cook skills to cook food for his allies as seen in "You Only Absorb Once".