Six-six is one of the three alien bounty hunters sent to Earth by Vilgax to take acquire the Omnitrix from Ben. He has purple armor and strange, clamp-like feet. He also has a jet-pack on his back. His armor is covered with pouches that hold many weapons and projectiles. He also has several small claws and a hand that extend from his shoulders. Unlike the other hunters, Sixsix only speaks in its own language, though the other two hunters still understand him.

Their second encounter with Six-six seemed to be a little bit more difficult for Ben to handle himself, so he teams up with the Galactic Enforcers to track him down. He plans to combine "Element X" and Bicenthium Alloy (Iron) to create a bomb enough to engulf the whole solar system.

Six-six is from the Storagg system and speaks in the universal Storaggian language.