Sean Richard Sellers (May 18, 1969 – February 4, 1999) was an American serial killer and one of 22 people in the United States since the reinstatement of capital punishment in 1976 to be executed for a crime committed while under the age of 18, and the only one to have been executed for a crime committed under the age of 17. Sellers was the first person to be executed for a crime committed at the age of 16 since 1959. His case drew worldwide attention due to his age as well as his jailhouse conversion to Christianity and his claim that demonic possession made him innocent of his crimes.

Sellers and his best friend, Richard Howard, had discussed how it would feel to kill someone. Sellers later confessed to the September 8, 1985, murder of Robert Paul Bower, a 36-year-old Circle K convenience store clerk who had refused to sell beer to Howard. According to Howard, who was present for but did not participate in the murder, Sellers "wanted to see what it feels like to kill somebody."

Sellers said he decided to kill his mother after a fight over his girlfriend, whom his mother did not like. He had served his mother several cups of coffee laden with rat poison, but it did not work. On March 5, 1986, Sellers shot and killed his mother Vonda, 32, and stepfather Paul "Lee" Bellofatto, 43, with a .44 caliber revolver while they were asleep in the bedroom of their Oklahoma City home. Wearing only underwear to limit blood spatter on himself, he first shot his stepfather. The shot awoke his mother, whom he shot in the face. Sellers tried to disguise his guilt by arranging the crime scene to look as if an intruder had committed the killings.

Howard testified that after the murders, Sellers came to his house and said he had killed his parents. Howard was also initially charged with first degree murder, but the charged was dismissed and he received a five-year suspended sentence for being an accessory after the fact after agreeing to testify against Sellers.

At his trial, Sellers said he was a practicing Satanist at the time of the murders and claimed that demonic possession (by the demon "Ezurate") caused him to murder his victims. In later documents, he claimed to have read The Satanic Bible by Anton LaVey "hundreds of times" between the ages of 15 and 16, when the crimes were committed, and in a "confession" letter written from prison, he reflected on this period of his life: "I got very involved in Satanism. I truly thought it was an honest way to live, and the rituals of it would enable me to control my life."

His attorneys also argued Sellers was addicted to the game Dungeons & Dragons, although Sellers would later write that the game had no part in his crimes and that "using my past as a common example of the effects of the game is either irrational or fanatical."

The jury refused to consider either claim, and Sellers was found guilty of multiple homicides and sentenced to death in 1986. At the time, Oklahoma law did not give juries the option of giving a life sentence without the possibility of parole (that choice became available in 1987). One juror later said that the jury feared that Sellers would be paroled in 7 to 15 years, and that this prison term was not lengthy enough. This led the jury to vote for a death sentence. However, other jurors denied that this was part of the deliberations.

Sellers became a Christian while in prison. His friends started a website on his behalf, and he campaigned for clemency based on his religious conversion, age, and involvement in Satanism. While on death row, Sellers made numerous appearances in the mass media, appearing on The Oprah Winfrey Show and on a notorious segment of Geraldo about Satanism. He appeared in documentaries about Satanism and serial killers for 48 Hours, MSNBC, WNS NEWS and the A&E Network. Sellers married in prison on February 14, 1995, but the marriage was annulled in 1997.