Jacqueline Susan Ansell-Lamb (21 September 1951 – 14 March 1970) and Barbara Janet Mayo (20 March 1946 – 12 October 1970) were two young women who were murdered in separate incidents in 1970. Both women were last seen hitch-hiking along motorways in England, and both were sexually assaulted before being strangled to death. Despite numerous public appeals for information and reconstructions, both murders remain unsolved. The perpetrator(s) of the murders of Ansell-Lamb and Mayo is sometimes referred to as the Monster of the Motorway or the Motorway Monster.