8. Spongebob Squarepants
Main Character Missing: Spongebob himself (technically).
Which Episode?: "The Algae's Always Greener" (Season 3, Episode 1A).
Is It Still Good?: Yes. I promise this is the last one where I could be cheating. Spongebob only appears in an alternate timeline (kind of like It's A Wonderful Life), and the episode focusses on one of the many attempts to steal the Krabby Patty Secret Formula by Plankton. The episode itself is fun, and his absence isn't particularly noticeable due to the fact that Alternate-Spongebob probably has a good minute or two of screen time. Besides, it's only a cartoon. Additionally, Spongebob is absent in a few holiday-themed shorts, but that's about it. Although on an interesting side note, Squidward appears in more episodes than Patrick does. Go figure.