Squilliam Fancyson is Squidward Tentacles' high school arch-rival. Squilliam attended Squidward's band class, and always puts him down. He is a very wealthy, snooty rival of Squidward who looks down at Squidward, for being just a lowly cashier in a greasy spoon.
Squilliam's first appearance was in "Band Geeks", where he challenged Squidward to play his band at the Bubble Bowl, commenting that he couldn't make it. Also, he comments that he is living Squidward's dream. However, Squilliam lied, and came anyway because he wanted to watch Squidward blow it. However, at the end of "Band Geeks", Squilliam, painfully aware of how good Squidward's band's performance is, has a heart attack and is rushed to the hospital, therefore, Squidward gets back at him. Squidward is painfully jealous and schemes constantly to show Squilliam he isn't a loser.
He later returns in "Squilliam Returns" and thinks that Squidward is the owner of a five-star restaurant. Once again, Squidward fails to impress him when chaos erupts. His last appearance is in "Professor Squidward".