John Thomas Straffen (27 February 1930 – 19 November 2007) was a British serial killer who was the longest-serving prisoner in British history. After killing two young girls in the summer of 1951, he was found to be unfit to plead and committed to Broadmoor Hospital. During a brief escape in 1952, he killed again. This time, Straffen was convicted of murder and sentenced to death. Reprieved because of his mental state, he had his sentence commuted to life imprisonment. Straffen remained in prison until his death more than 55 years later.