Quatnja

Mr Quatnja was a businessman. His products pacified the rowdier elements of a population. Quatnja travelled to Earth because of its "protected status," allowing him to hide from the galactic authorities.

When one of his employees stole some R'ochni to sell on, Quatnja killed him. Shortly after, Gwen Cooper and Jack Harkness burned his warehouse to the ground. (COMIC: Somebody Else's Problem: A Gwen Cooper Story)