Squilliam Fancyson III is a very wealthy and self-serving octopus who first appears in the episode "Band Geeks" and is voiced by Dee Bradley Baker. He met Squidward Tentacles in high school band class and became his rival. Squilliam has succeeded in everything Squidward has failed in and thus looks down upon his rival. Squidward is painfully jealous and wishes to prove to Squilliam that he is not a loser.

Like other octopus characters, Squilliam's character model is nearly identical to Squidward's, but he has a unibrow and wears a fancy maroon robe. He owns a private yacht, a private lake, a private heliport, a private island, and a balloon/casino. He owns a fancy tower which makes an appearance in "House Fancy."