John Allen Muhammad (born John Allen Williams; December 31, 1960 – November 10, 2009) was an American serial killer who, along with his partner and accomplice Lee Boyd Malvo (then aged 17), carried out the D.C. sniper attacks of October 2002, killing seventeen people. Muhammad and Malvo were arrested in connection with the attacks on October 24, 2002, following tips from alert citizens.

A native of Baton Rouge, Louisiana, Muhammad changed his surname after joining the Nation of Islam in 1987. At Muhammad's trial, the prosecution claimed that the attacks were part of a plot to kill his ex-wife and regain custody of his children, but the judge ruled that there was insufficient evidence to support this argument.

Muhammad's trial for one of the murders (of Dean Harold Meyers in Prince William County, Virginia) began in October 2003, and ended with his conviction for capital murder. Four months later he was sentenced to death. While awaiting execution in Virginia, in August 2005, Muhammad was extradited to Maryland for trial, resulting in his conviction on six counts of first-degree murder in May 2006. Upon completion of the trial activity in Maryland, he was returned to Virginia pending an agreement with another state or the District of Columbia seeking to try him. He was not tried on additional charges in other Virginia jurisdictions and faced potential trials in three other states and the District of Columbia involving other murders and attempted murders. All appeals of his conviction for killing Meyers had been rejected. Appeals for Muhammad's other trials remained pending at the time of his execution.

Muhammad was executed by lethal injection on November 10, 2009, at 9:06 p.m. EST at the Greensville Correctional Center near Jarratt, Virginia, and was pronounced dead at 9:11 p.m. EST. Muhammad declined to make a final statement.