Vilgax is a Brute warrior who was a Chimera Su Generis from Planet Vilgaxia. He wants the Omnitrix but unintentionally destroyed it after the Season Finale of Ben 10,000. He then tried to take over Earth but first from the Plumber Base in Rushmore. He is the main antagonist for the Season 1 Finale.
Phobus is a rival of Thanatos and god of fear. He once used to live in Rome but was kicked out after Christianity took over. He now dwells in the pit of Violence in the Pacific Ocean. He is aching for revenge in the pit by absorbing fears from ships and airplanes when it goes near his dwelling. In the Classical Age, Thanatos explains that Phobus always disturbs his works. In “In Training”, Phobus made a new home in the west coast of England. There is named himself Harold Subphos. There, he could absorb the powers from the Heavenly Angels but was delayed by Etoile, Ben and Zeszon.
Hel is the goddess of underworld and Spirits. She is an Omnitrix bounty hunter. She once used to live in Norway and Denmark as the goddess of sorcery but was eliminated after Christianity took over the Vikings. She went to the Pacific Ocean where she made her own Underworld. She and Ghostfreak worked together but was thwarted by Benjamin Tennyson in the early series before Ken 10 or Ben 10,000 or Stan 10. She will be the main villain for the second season.
Black-out is a hypnotist who squabbles with Ben 10,000. He became zapped by the Black Light and is now a top greedy villain. He freed all the villains at the end and the beginning of Ben 10,000 and Omnitrix Power.
Atlas is a mad scientist who searches for aliens and hunt them down. Atlas in a strange experiment was turned into a Chimera with head of the Lion, ear of the rabbit, legs of the rhino and body of a horse. After testing himself, he found that he can also turn back into his human form. Ben 10,000 is still oblivious of Atlas.
Dark Bat) is a scientist who is searching for a medicine to save his deafness. He finally found it and drank it and become a mutant with echo-location and Chiropteran controlling stuff. Later, he used this power to steal money to save his wife from being dead.