Sixsix is one of the three bounty hunters after the Omnitrix. Out of the three, he is the only one to talk in his own language, while the others talked in English. He also has a jet-pack. His armor is covered with pouches that hold various weapons and projectiles, such as twin blasters, laser discs, a buzz saw, laser blade and whip, a sonic weapon, throwing pikes, grenades, bolas, rockets, and several tentacle-mounted lasers coming out of his back pack. He also has several very strange small claws and hands that extend from his shoulders that are usually used to throw the small pikes coming out of his jet pack, or bombs when he is using his blasters. Sixsix is a Sotoraggian from the home world Sotoragg.
Sixsix appears in the episode "Hunted", "The Galactic Enforcers" teaming up with Vulkanus as part of his plan to combine Element X with bisynthium alloy (an unspecified form of iron ore) to create an explosive capable of wiping out an entire solar system.

He appears in Ben's dream world in "Perfect Day"

He appears as a henchman in Ben 10: Secrets of the Omnitrix, where his helmet is broken, revealing a gray-skinned creature beneath. Strangely, he seems to become more feral after this happens: Vilgax attaches a leash to him in order to keep him under control.
Sixsix is different from his own species because his appearance was because of a mutation.
Sixsix has made four appearances in the Ben 10 Series.
Additionally a version of the bounty hunter Sixsix will appear in X Equals Ben Plus 2.
Sixsix is some how related to Sevenseven.

Sixsix's First Appearance
Hunted

Sixsix's Last Appearance
Ben 10: Secret Of The Omnitrix