Since SpongeBob is a main character and the titular character, meaning he appears in every episode. Though it also appears that ever since the seasons that came after the movie his voice had gotten a bit higher then when from he had a more deepish voice. SpongeBob's best friend is known to be Patrick Star the dim-witted pink star fish who appeared to have gotten dumber through the seasons, in other words as the series progresses Patrick has gotten much dumber. SpongeBob though as well appears to have gotten more dumber as the series progresses as in one episode he finds out were boogers came from. Also well SpongeBob also has his pet snail Gary the Snail who is equivalent to a cat. Though SpongeBob and Squidward both turned into snails in the episode I Was a Teenage Gary.
Appears in every episode.
SpongeBob is a yellow sea sponge that looks like a cleaning sponge. He is a yellow sea sponge with olive green holes around his body. He usaully wears a white shirt with a red tie and brown pants that over-lap his shirt and a black belt that goes around the pants. He also wears socks with red & blue stripes(3). And he also wears black shows,but while working at the Krusty Krab wears a hat whith a dark blue anchor.
His parents look like real sponges but he looks more like a cleaning sponge.
His second proto-type was SpongeBoy who looked exactly like SpongeBob but with a green hat.
In the episode The Abrasive Side the abrasive side made him look like a real cleaning sponge as a joke.
SpongeBob is voiced by Tom Kenny.