The series conclusion features the return of Vilgax and the debut of the Ultimatrix. Seeing Ben lose the original Omnitrix and make a desperate sacrifice to stop his greatest foe provided a high-octane bridge into the next series, Ultimate Alien . 3. "The Gauntlet" (Season 1, Episode 9)
: Gwen travels back in time to prevent the accident that mutated Kevin. She accidentally creates a dystopian alternate timeline, proving some things cannot be changed. ben 10 alien force all episodes top
Gwen's brother Ken disappears, leading the team to a Highbreed factory. The stakes feel incredibly high, culminating in a devastating sacrifice. The series conclusion features the return of Vilgax
The adventure awaits!
Moves from a selfish ex-convict to a trusted, loyal friend, with his relationship with Gwen being a highlight of the series. "The Gauntlet" (Season 1, Episode 9) : Gwen
Introduces Alan Albright, a half-human, half-Pyronite Plumber's kid. It does a great job expanding the world-building regarding alien hybrids on Earth.
Vilgax seeks Ben's help after Vilgaxia is overtaken by Ghostfreak. It features excellent horror elements and brings back one of the original series' creepiest villains.