Cold North Killers: Canadian Serial Murder is a 2012 Canadian non-fiction book written by Lee Mellor and published by Dundurn Press. It documents the lives of sixty Canadian serial killers, with the earliest being Edward H. Rulloff and the most recent being Russell Williams. The book uses Katherine Ramsland's interpretation of what constitutes a serial killer—someone who has killed at least two people on two occasions, and who attempted to or likely would have killed again—as outlined in her 2007 book The Human Predator. Cold North Killer's own definition of what constitutes a Canadian serial killer includes both Canadians who committed murder abroad (such as Keith Hunter Jesperson and Gordon Stewart Northcott) and non-Canadians who committed murder in Canada (like William Dean Christensen