Marion Albert Pruett (1950 – April 12, 1999) was a serial killer executed in Arkansas by lethal injection. Marion Pruett was sentenced to death for the October 12, 1981, murder of Bobbie Jean Robertson, a convenience store clerk in Fort Smith, Arkansas. She was one of at least five people Pruett killed; three of which were killed during that same week.
Marion Pruett is known to have killed Peggy Lowe, a Mississippi loan officer, kidnapped and murdered Arkansas convenience store clerk Bobbie Jean Robertson, and two others in Colorado. He also murdered his wife in New Mexico.
In April 1981, his common-law wife Pamela Sue Barker, also known as Michelle Lynn Pearson, was found dead in Rio Rancho, New Mexico. She had been bludgeoned with a ballpeen hammer and had been burned.
Pruett abducted Robertson from a Fort Smith convenience store where she worked, took her to a wooded area behind the store and shot her. From death row, he asked a Mississippi newspaper to pay him $20,000 to disclose the location of Barker's engagement ring (his offer was refused) and offered to reveal the location of a Florida victim's body in exchange for a paid appearance on Geraldo. He also killed two 7-Eleven clerks .
Pruett was interviewed by the A&E Television Networks show American Justice in an episode titled “Dealing With The Devil”. The episode included footage of Pruett two weeks before he was executed and interviews with his victims' relatives and the government official who put him in the witness protection program.
At his New Mexico trial for Barker's murder, Pruett said that he had killed people and committed robberies to support a cocaine habit that sometimes ran up to $4,000 a week. However, he denied killing his wife. 
Pruett was executed by lethal injection at 9:00 p.m. at the Cummins unit of the Arkansas Department of Corrections on Tuesday, April 12, 1999. Pruett was the 19th person executed by the state of Arkansas since Furman v. Georgia, , after new capital punishment laws were passed in Arkansas and that came into force on March 23, 1973.