Vulkanus

Vulkanus (voiced by John DiMaggio) is a Detrovite (the same species as Technorg) who partners up with Sixsix in order to build a weapon capable of destroying a solar system.

Original series
In the original series, he is almost always seen with Sixsix. Unlike Technorg, he isn't enhanced in any way. He is stopped by Ben and the Galactic Enforcers in the episode The Galactic Enforcers. He reappears in Ben's dream world in Perfect Day working alongside Sixsix again, and in the start of the future episode Ken 10, where he was defeated by Ben 10,000 and was transported to the Null Void.

Alien Force
Vulkanus makes a brief appearance in Ben 10: Alien Force in the episode Kevin's Big Score. According to Vulkanus, he was betrayed by Kevin during a "counterfeit isotope" scam a few years earlier. Kevin left him holding the merchandise when The Plumbers arrived, and though he managed to escape, the Plumbers destroyed his ship. Unable to leave Earth, he resorted to trading low-level alien technology to get by. When Kevin arrives looking to obtain an important item (a holo-disc from Grandpa Max), Vulkanus decides to get back at him for the betrayal by forcing Kevin to absorb a small piece of Taedenite, the rarest living gem in the galaxy. This causes Kevin's body to mass-produce the gem, thus giving Vulkanus an endless supply. However, he is foiled by Ben, who uses Big Chill to literally freeze off his armor, revealing that Vulkanus is really nothing more than a minuscule alien in a giant suit. Rather than attempt to arrest him, however, Kevin leaves Vulkanus with the small fortune in crystals he had managed to chip off beforehand, considering it as payment for his past actions.

He makes a brief appearance in Con of Rath. When Ben (as Rath) and Gwen discover from Kevin they need Taedenite to power their ship, Gwen tells Kevin that every time they come across Taedenite they run into Vulkanus. Kevin says their imaging things only to be confronted by Vulkanus. Kevin tries to negotiate with Vulkanus using a gold credit cube (an alien form of currency with no spending limit) but Vulkanus holds firm. He is defeated by Rath who ruined most of his Taedenite. Beaten Vulkanus is forced to hand over his remaining Taedenite.

Ultimate Alien
Vulkanus returns in Hit 'Em Where They Live with Charmcaster, Sevenseven, and Zombozo and tries to attack Ben's family. He may be part of Zombozo's new Circus Freak Trio. If so, he may be Thumbskull's replacement.

Appearances

 * Ben 10
 * Season Two
 * The Galactic Enforcers
 * Season Four
 * Perfect Day
 * Ken 10
 * Ben 10: Alien Force
 * Season One
 * Kevin's Big Score
 * Season Three
 * Inferno
 * Con of Rath
 * Ben 10: Ultimate Alien
 * Season One
 * Hit 'Em Where They Live