Ebonite

Mister  was an alien technology trader. He was a gestalt being.

Biography
He had an agreement with Cleo Hunsicker requiring her to deliver him all alien artefacts that the Cult of the Black Pyramid did not require. When he detected a time anomaly in the journal left to Cindy Wu by Gabby Gonzalez, he demanded the journal to be handed to him. Only the interference of Jack Harkness saved the day. Jack shot Mr Ebonite causing him to break into many little copies of himself. (COMIC: Cindy, Cleo and the Magic Sketchbook)

He abducted Jack Harkness, Cindy Wu and Cleo. The Monaxi, his servants, activated a time bridge and brought the Tenth Doctor and his crew to the Arena of Fear as well. After Ebonite stated that "anybody could be their enemies", Tony, Gabby and Unta were under his control inside the Arena of Fear.

He was defeated by Gabby, who had released herself from his control. Afterwards, he split into many small versions of himself, which ran away, some of them being killed. (COMIC: Arena of Fear)

Personality
Ebonite was a ruthless, cutthroat, scheming, manipulative, murderous and intelligent hiver whose ultimate goal was to achieve immortality. He was described by Captain Jack as being a monomaniac, caring only about himself and holding no value in the lives of others. He would usually only let people live if they proved useful and was more than willing to kill them once they had outlived that usefulness or annoyed him to much.

The Hiver was also highly sadistic, taking great delight in cruelly taunting his adversaries as well as watching his pawns hurt each other in his brutal mind games or fighting to the death.

In spite of his cruelty and sadism, Ebonite proved to be very cowardly in the end and would often retreat in humiliating fashion as soon as the tables turned against him and in favor of the Doctor and his allies.

Abilities
Ebonite was a gestalt being comprised of what seemed like hundreds of smaller copies of himself. Though he appeared as a singular entity, if hit or shot with a powerful enough weapon, his body would break into these smaller copies who would then flee to reform.

Ebonite was capable of teleporting or rendering himself intangible by transforming into a cloud of black vapor and could even fly or levitate in this form.

He also possessed psychic abilities that included mind control. He could mentally control several people at once, manipulate and erase memories and even granted Gabby Gonzales access to her hidden block transfer powers.