Dash Baxter serves as an expy for Flash Thompson: they're both Jerk Jocks who bully their protagonist while at the same time being the biggest fan of his superhero alter ego.
Jack Fenton is an Expy of Mr. Fantastic. Both are scientists and inventors who have made a portal to another dimension, have white streaks in their hair, and an archenemy who has been holding a grudge on them for years.
Star is Veronica Star from The Fairly OddParents!, all grown up. Same name? Check. Blonde? Check. Satellite to a non-white Rich Bitch? Check. A cheerleader? Check. The only major difference is that she is voiced by Tara Strong, not Grey DeLisle.
Tucker is an expy of Steve Urkel from Family Matters, only without the annoying nasal voice.
The Guys In White are a pretty obvious expy/parody of the Men in Black comic/film series, replacing aliens with ghosts.
Hobson from "Livin' Large" has the same job, appearance, personality, voice, and name as John Gielgud's character from Arthur (1981).
Dani Phantom is one to X-23, being female clones of a hero who were made by the Hero's enemy but ultimately sided with said Hero. For Dani's case it is Danny, for X-23, Wolverine.
Butch Hartman has described Vlad Masters/Plasmius as the "Lex Luthor" of the series, in that he's a billionaire who serves as the Arch-Enemy of the hero that puts on a seemingly charming act in the presence of others and is motivated by his pettiness and ego to commit acts of villainy. They also have a very unhealthy hatred for someone, Superman and Jack Fenton for Lex and Vlad respectively, that motivates most if not all of their plans. His becoming mayor in the final season also mirrors how Luthor was president for a time.
Skulker is one of Kraven the Hunter, being a supervillainous big-game hunter who wants to make the main character his quarry.
