Rx-1

Aka Security Chief Rex Warren

Despite appearing human, RX-1 is actually an artificial life form (as far as we know) created in a secret Imperial Laboratory. Something went wrong and the orders were to purge the experiment, but Anna instead freed it and fled, and eventually they both joined the crew of the Destiny, where he puts his combat abilities and shape shifting to good use on covert and not so covert missions.

Once out of the lab, RX found he had a natural talent for salvage and other black market operations. He has shown a remarkable lack of restraint in the areas of theft and other crime, going even so far as to rob an an alternate universe version of himself.

It was eventually revealed he was actually created partly from a mind transfer from the mostly deceased body of Rex, Anna's brother.