James Ryan O'Neill (born Leigh Anthony Bridgart in 1947) is an Australian convicted murderer and suspected serial killer, currently serving a life sentence in Tasmania for a murder he committed in February 1975. Allegations have been made that O'Neill also murdered a number of other children in several Australian states from the mid-1960s whilst he was still a teenager through to the murder that he was imprisoned for in 1975. He is currently Tasmania's longest-serving prisoner for a single offence.