Squilliam FancysonIII is Squidward Tentacles' arch-rival whom he met in high school band class. He is a very wealthy, self-serving, unibrow-endowed octopus who has succeeded in everything Squidward has failed in and thus looks down upon him. Squidward is painfully jealous and constantly attempts to show Squilliam he's not a loser, with varying results.
Squilliam is an octopus with six tentacles. He wears a red and black robe and has an ascot. Squilliam has a large black single eyebrow, or unibrow. He has had it in every episode. In "Band Geeks," he shows pride in it when he calls it "big and valuable." In "Professor Squidward," this feature is how the police told him apart from Squidward. In "House Fancy," Squilliam has a large replica of his unibrow that is made entirely out of gilded doorknobs.
Squilliam is rich and fancy. He makes no secret that he considers himself superior to others due to his enormous wealth. He is mean, selfish, sadistic, and arrogant, and takes great pleasure in asserting his perceived superiority over middle-class citizens like his arch-rival Squidward. He also speaks in a very mocking tone, placing great emphasis on his low regard for Squidward and an equally large amount of inflated praise in his lavish lifestyle. Even though he's a jerk, he somehow makes friends easily, probably for letting people in his private jet, yacht, balloon/casino, etc.
Squilliam is narcissistic and he considers himself to be undeniably handsome, even though he and Squidward (and every other octopus) look alike, save for the unibrow.
Squilliam has made appearances in 8 episodes so far. He plays a major role in the episodes "Band Geeks," "Squilliam Returns," and "House Fancy."
Squilliam's first appearance was in this episode. He challenges Squidward to play his band at the Bubble Bowl, as his own band could not make it. However, at the end of the episode, Squilliam arrives at the Bubble Bowl anyway to watch Squidward fail (which may imply that he was just setting up Squidward to make a fool of himself), but upon seeing the band's surprisingly good performance, Squilliam appears to have a heart attack and is rushed to the hospital on a stretcher.
Squidward tells Squilliam that he is the owner of a five-star restaurant in an attempt to show him up. Although Squilliam is initially impressed by SpongeBob's newfound fine dining expertise, Squidward is ultimately humiliated when SpongeBob cannot remember his own name and goes insane and destroys the restaurant.
Squilliam's ridiculously luxurious house is featured on the TV show of the same name. The house features, among other things, a golden toilet, an elevator with a built-in hot tub, and a massive sculpture of his unibrow made entirely out of gilded doorknobs. Squidward's jealousy once again gets the better of him when he calls the show's host, Nicholas Withers, claiming that his house is better than Squilliam's. Although Squidward's house is destroyed as a result of his attempts to make it fancier, Withers sees his destroyed house as a work of art and proclaims it to be better than Squilliam's. Squilliam breaks down and falls over, in tears, as he is once again upstaged by Squidward.
Squilliam also appears at the end of "I ♥ Dancing," where after Squidward is given the part of a line dancer for Squilliam, he begins to abusively train him in the same manner that Squidward did to SpongeBob.
In an alternate timeline, SpongeBob and Patrick from the original timeline walk by him putting up a sign in Bikini Bottom when Man Ray took over. This is so far the last appearance where he has a speaking role.
Squidward and Squilliam absolutely hate each other because Squilliam brags about everything he succeeds in to Squidward (which Squidward usually fails in) and is always mocking him for being of lower class.
"Sounds as though you've got a dying animal to attend to, eh old chum?"
"I'm filthy stinkin' rich!"
"It's a gilded doorknob."
"Come on everyone; let's go take a ride in my balloon slash casino!"
(referring to his unibrow) "It's big and valuable. I'm a leader of a big fancy band right now. And we're supposed to play the Bubble Bowl next week."
"Squidward Tentacles has the fanciest restaurant in Bikini Bottom, and he does not suck eggs (After Squidward tricks him into thinking he actually does own a 5-star restaurant)."
"Explain what? That you, Squidward Tentacles, voted most likely to suck eggs in high school, (walks into Krusty Krab) are trying to pass off a lousy burger stand as a five-star... (Gulps) ...restaurant!?"
Squilliam shares some similarities with Remy Buxaplenty from another Nickelodeon show, The Fairly OddParents. Among them, both Remy and Squilliam are rich, are arch-rivals with main characters (Timmy Turner and Squidward), and are both voiced by Dee Bradley Baker, however, unlike Squilliam, who has lots of friends, Remy has little to no friends.
Squilliam also shares some similarities with Suneo Honekawa from Japanese animated children television series called Doraemon. Among them, both Squilliam and Suneo are rich and snob, flaunting their wealth, and taunting their rivals (Squidward and Nobita). However, unlike Suneo, who is one of Nobita's frenemy, Squilliam never befriends with Squidward.
Squilliam also shares some similarities with Gladstone Gander from Disney franchise. Among them, both Gladstone and Squilliam are lucky and wanted to outsmart their rivals (Donald Duck and Squidward). However, unlike Squilliam, never related to Squidward or having a girlfriend, Gladstone related to Donald as his cousin and has a crush on Daisy.
Squilliam has not appeared in the series since the season 10 episode "Code Yellow." Even then, that was only his likeness as a nose. He has not appeared as a character since Season 7's Back to the Past.