Jack Ruby was an American citizen who killed Lee Harvey Oswald.
The owner of the Carousel Club, Ruby was privy to the existence of mutants as his clientele included the Friends of Humanity and the Purifiers, groups whose ideology was infulenced by Edwin Partridge. As a result, one of Ruby's exotic dancers, Arleen Adams, was soon murdered by one of the two groups.
Shortly after hearing of President Kennedy's death, an enraged Jack Ruby killed Lee Harvey Oswald during a police transfer. Detained by the police, he claimed to have done so to spare Kennedy's wife grief. However, Ruby was then given a vaccination by a nurse which he soon found to have contained cancer cells. Ruby's mind was later warped, with him forgetting how he even arrived in police custody. He was then sentenced to death, but died in the same room Oswald did in due to the lung cancer.