Devin Levin

Devin Levin is a false memory planted in Max Tennyson's head by Servantis.

Appearance
In appearance, Devin was outwardly indistinguishable from a human. The same is true for Kevin and other Osmosians that are not fully mature (Dwayne McDuffie confirmed that Osmosians live for hundreds of years and it is at least a century before an Osmosian is fully mature, they also grow small horns on their head) and Devin lacks horns on his head (it's possible he has them, but they are hidden in his hair or Osmosians can breed before being fully mature).

Alien Force
Devin was first mentioned in If All Else Fails, and, so-far, has only appeared in a photograph and in a flashback in Vendetta. Max describes Devin as "energetic" and "likable".

In the memory of Max, they were trying to escape from Ragnarok, a dangerous criminal who steals the energy of stars and sells them to the highest bidder. The key to his ship having been stolen by Devin, Ragnarok was in pursuit to retrieve it. Having managed to render their ship dead in space, Ragnarok boarded and attacked them, demanding his key back.

When none of his or Max's weapons were effective against Ragnarok, Devin was forced to absorb electricity to buy them some time. While Devin was able to retain his sanity (due to his experience), Ragnarok managed to prevent Max from using a Null Void Projector and trapped them both under heavy fire. Devin shielded Max from Ragnarok's attack, buying Max a chance to get his hands on the Null Void Projector and send Ragnarok to the Null Void.

Devin died in Max's arms, expressing that dying to save Earth wasn't a bad way to go. His last request was for Max to tell his wife and son that he loved them.

Omniverse
In The Rooters of All Evil, it was revealed Max's that Devin was a false memory Servantis gave to him to keep an eye on Kevin and also his other experiments. In reality, Devin Levin never existed.

Ben 10: Alien Force

 * Vendetta (first appearance; flashback)

Trivia

 * Kevin and his alternate timeline grandson Devlin, along with Paradox, bear strong resemblances to Devin.