Androvax was a Veil, and an enemy of Sarah Jane Smith. Rather like the Doctor, he was supposedly the last of his kind.
Biography
Androvax's life before his planet's destruction is unknown. He left to travel the stars and returned to find his race extinct after their sun was extinguished. Distraught over the loss of his world, he grew jealous of other species, and sought to destroy their planets, teaching them what he had come to believe: That the truth of the universe was destruction. He became the highest on the Judoon's most wanted list, being wanted in five galaxies for twelve counts of global destruction.
He was eventually caught by Captain Tybo, but during transport the ship crashed, allowing Androvax to escape. He knocked out Tybo and escaped, taking over the body of a young girl. However, when Sarah Jane Smith detected him he revealed himself, stunned Sarah Jane and entered her body instead. He then returned to her home in Sarah's body and instructed Mr Smith to self destruct, before proceeding to the Genetec Systems and instructing the microscopic nanoforms to build him a ship.
Androvax was finally caught when Luke threatened to sabotage the ship, and ultimately stopped the Nanoforms from destroying the planet. The Veil was then sentenced to execution. (SJA: Prisoner of the Judoon)
Abilities
Androvax's species were capable of "body-snatching"; literally jumping into another being's body and taking complete control of that individual, though some were able to resist to a certain degree. While in a host body, Androvax was able to stick out his own forked tongue. Androvax himself was quite cunning, evidently from his Two-By-Four approach to improvise with whatever he had access to, single-handedly destroying twelve planets and avoiding the Judoon for a undetermined period of time, taking advantage of the nanites and Mr. Smith. (SJA: Prisoner of the Judoon)
Personality
Androvax acted outwardly cruel and malicious, deeming the purpose of the universe to be destruction and did what he could to create as much of it as possible. Underneath it all however, Androvax was lonely and depressed, it was heavily implied by Sarah Jane that he caused death and destruction to ease his own suffering. (SJA: Prisoner of the Judoon)