John William Cooper, also known as The Bullseye Killer, is a Welsh serial killer. On 26 May 2011, he was given a whole life order for the 1985 double murder of siblings Richard and Helen Thomas, and the 1989 double murder of Peter and Gwenda Dixon. The murders were known in the media as the "Pembrokeshire Murders" or the "Coastal Murders". Cooper was also sentenced for the rape of a 16-year-old girl and a sexual assault on a 15-year-old girl, both carried out while a group of five teenagers were held at gunpoint in March 1996, in a wooded area behind the Mount Estate in Cooper's hometown of Milford Haven, Pembrokeshire.