Quatnja

Mr Quatnja was a businessman, an alien drug lord of unknown species who travelled to Earth because of its "protected status," allowing him to hide from the galactic authorities. He claimed that his products pacified the rowdier elements of the alien population on Earth and that Torchwood turned a blind eye to his operation because of this.

One of his employees stole some of his drug R'ochni to sell on the side. Unfortunately he sold some of it to humans, whose biology couldn't process it. When used by humans it turned them into alien mutations, killing them in the process. Gwen Cooper happened to be in a bar having a drink with some friends when the drug dealer sold his stolen gains and noticed his inhuman anatomy.

Gwen persued the dealer and eventually caught up with him and forced him to take her to Quatnja. In the ensuing confrontation Quatnja killed the employee for his stupidity in selling to humans, bringing the attention to them and threatened Gwen. The warehouse where he conducted business also caught fire during this and burned to the ground.

Gwen was rescued by Jack Harkness and the pair escaped in the Torchwood SUV. When Gwen confronted Jack about Quatnja's statements, Jack claimed that he didn't deliberately turn a blind eye but the operation had genuinely slipped under his radar. (COMIC: Somebody Else's Problem: A Gwen Cooper Story)