Gilbert Paul Jordan (December 12, 1931 – July 7, 2006), known as the "Boozing Barber", was a Canadian serial killer who is believed to have committed the so-called "alcohol murders" in Vancouver, Canada.
Lee Boyd Malvo (born February 18, 1985), also known as John Lee Malvo, is a convicted murderer who, along with John Allen Muhammad, committed murders in connection with the Beltway sniper attacks in the Washington Metropolitan Area over a three-week period in October 2002.
 Currently, he is serving multiple life sentences at Red Onion State Prison in Virginia, a supermax prison.
 Muhammad was executed in 2009.
 Although the two men's actions were classified by the media as psychopathy attributable to serial killer characteristics, researchers have debated whether or not their psychopathy meets this classification or that of spree killing.
 In 2012, Malvo claimed that he was sexually abused by Muhammad.
A serial killer is typically a person who murders three or more people, usually in service of abnormal psychological gratification, with the murders taking place over more than a month and including a significant break (a "cooling off period") between them.
 Different authorities apply different criteria when designating serial killers; while most set a threshold of three murders, others extend it to four or lessen it to two.
 The Federal Bureau of Investigation (FBI), for example, defines serial killing as "a series of two or more murders, committed as separate events, usually, but not always, by one offender acting alone".
The Texarkana Moonlight Murders, a term coined by the news media, references the unsolved murders committed in and around Texarkana in the spring of 1946 by an unidentified serial killer known as the "Phantom Killer", or "Phantom Slayer".
 The killer is credited with attacking eight people within ten weeks, five of whom were killed.
 The attacks happened on weekends between February 22, 1946 and May 3, 1946.
 The first two victims, Jimmy Hollis and Mary Larey, survived.
 Some police officers are not sure if their attack was connected with the murders.
 The first double murder, which involved Richard Griffin and Polly Ann Moore, happened four weeks later.
 The second double-homicide, involving Paul Martin and Betty Jo Booker, occurred exactly three weeks from the first murders.
 The Texas Rangers came in to investigate, including the famous M. T. "Lone Wolf" Gonzaullas.
 Finally, almost exactly three weeks later, Virgil Starks was killed and his wife, Katie, was severely wounded.
 Most officials no longer connect that attack to the other murders.
 Contrary to popular belief, the killer did not attack during a full moon, but did strike late at night.
David G. Meirhofer (June 8, 1949 – September 29, 1974) was an American serial killer who committed four murders in rural Montana between 1967 and 1974 — three of them children.
 At the time, the Federal Bureau of Investigation was developing a new method of tracking killers called offender profiling, and Meirhofer was the first serial killer to be investigated using the technique.
 Offender profiling is a method used to learn clues about the characteristics of an unknown killer from evidence at the scene of the crime and establish their behavioural patterns before they reach the height of their criminality.
Robert William "Willy" Pickton (born October 24, 1949) of Port Coquitlam, British Columbia, Canada, is a Canadian serial killer convicted in 2007 of the second-degree murders of six women.
 He was also charged with the deaths of an additional 20 women, many of them from Vancouver's Downtown Eastside; however, these charges were stayed by the Crown in 2010.
 In December 2007, he was sentenced to life in prison, with no possibility of parole for 25 years – the longest sentence then available for murder under Canadian law.
Paul Kenneth Bernardo (born 27 August 1964), also known as Paul Jason Teale, is a Canadian serial killer and serial rapist.
 He is known for several rapes in the eastern Metropolitan Toronto city of Scarborough, and a series of highly publicized sexual assaults, tortures and murders committed with his wife, Karla Homolka.
Cody Alan Legebekoff (born  1990 ) is a Canadian serial killer convicted in 2014 by the British Columbia Supreme Court of murdering three women and a teenage girl, between 2009 and 2010, in or near the City of Prince George, British Columbia.
 This trial of one of Canada's youngest serial killers drew national attention.
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 separate 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 Christenson and Earle Nelson).
Earle Leonard Nelson, known as "the Gorilla Man," (May 12, 1897January 13, 1928) was an American serial killer.

Question: Cold North Killers: Canadian Serial Murder includes a serial killer who committed murders in Canada, but was of what nationality?
Answer: American