Peter William Sutcliffe (2 June 1946 – 13 November 2020), also known as Peter William Coonan, was an English serial killer who was dubbed the Yorkshire Ripper (an allusion to Jack the Ripper) by the press. On 22 May 1981, he was found guilty of murdering 13 women and attempting to murder seven others between 1975 and 1980.: 144  He was sentenced to 20 concurrent sentences of life imprisonment, which were converted to a whole life order in 2010. Two of Sutcliffe's murders took place in Manchester; all the others were in West Yorkshire.

Sutcliffe initially attacked women and girls in residential areas, but appears to have shifted his focus to red-light districts because he was attracted by the vulnerability of prostitutes, and perceived ambivalence of police to prostitutes' safety at the time. He had allegedly regularly used the services of prostitutes in Leeds and Bradford. After his arrest in Sheffield by South Yorkshire Police for driving with false number plates in January 1981, Sutcliffe was transferred to West Yorkshire Police, which questioned him about the killings. He confessed to being the perpetrator, saying that the voice of God had sent him on a mission to kill prostitutes. At his trial, Sutcliffe pleaded not guilty to murder on grounds of diminished responsibility, but he was convicted of murder on a majority verdict. Following his conviction, Sutcliffe began using his mother's maiden name of Coonan.

The search for Sutcliffe was one of the largest and most expensive manhunts in British history, and West Yorkshire Police was criticised for its failure to catch him despite having interviewed him nine times in the course of its five-year investigation. Owing to the sensational nature of the case, the police handled an exceptional amount of information, some of it misleading (including the Wearside Jack hoax recorded message and letters purporting to be from the "Ripper"). Following Sutcliffe's conviction, the government ordered a review of the investigation, conducted by the Inspector of Constabulary Lawrence Byford, known as the "Byford Report". The findings were made fully public in 2006, and confirmed the validity of the criticism against the force. The report led to changes to investigative procedures that were adopted across UK police forces. In 2019, The Guardian described the manhunt as "stunningly mishandled". Since his conviction in 1981 Sutcliffe has been linked to a number of other unsolved murders and attacks.

Sutcliffe was transferred from prison to Broadmoor Hospital in March 1984 after being diagnosed with paranoid schizophrenia. The High Court dismissed an appeal by Sutcliffe in 2010, confirming that he would serve a whole life order and never be released from custody. In August 2016, it was ruled that Sutcliffe was mentally fit to be returned to prison, and he was transferred that month to HM Prison Frankland in Durham. He died from COVID-19-related complications in hospital, while in prison custody on 13 November 2020, at the age of 74.