Mark David Chapman (born May 10, 1955 in Fort Worth, Texas) is an American who shot and killed musician and activist John Lennon on December 8, 1980 in New York City

Before his trial began, Chapman was allowed to plead guilty to second degree murder and was sentenced to a prison term of 20 years to life despite being diagnosed as delusional and possibly psychotic. He remains incarcerated at Attica Correctional Facility in New York, having been denied parole four times. His applications for parole have been opposed by Lennon's widow, Yoko Ono, as well as a grassroots public campaign.