Joseph James DeAngelo Jr. (born November 8, 1945) is an American serial killer known as the Golden State Killer, the Original Night Stalker, and the East Area Rapist, who committed at least 13 murders and numerous rapes and burglaries across California between 1974 and 1986. The crimes began in northern California where DeAngelo committed a minimum of 120 burglaries and one murder in the San Joaquin Valley before moving to Sacramento County, where he committed at least 51 rapes and two more murders from 1976 to 1979. In southern California, DeAngelo murdered at least ten people from 1979 until 1986 before going dormant.

After committing a series of highly publicized burglaries in and around Visalia, DeAngelo escalated to raping victims in east Sacramento and was additionally linked to attacks in Stockton, Modesto, and Contra Costa County. DeAngelo committed serial murders in Santa Barbara, Ventura, and Orange counties from 1979 to 1986. He is believed to have taunted and threatened both victims and police via obscene phone calls and possibly written communications. During the decades-long investigation, several suspects were cleared through DNA evidence, alibis or other investigative methods.

In 2001, DNA testing indicated that the East Area Rapist and the Original Night Stalker were the same person. The case was a factor in the establishment of California's DNA database, which collects DNA from all accused and convicted felons in California and has been called second only to Virginia's in effectiveness in solving cold cases. In an attempt to increase awareness, crime writer Michelle McNamara coined the name "Golden State Killer".

In 2016, the Federal Bureau of Investigation (FBI) and local law enforcement agencies held a news conference to announce a renewed nationwide effort, offering a $50,000 reward for the Golden State Killer's capture. On April 24, 2018, California authorities charged 72-year-old DeAngelo with eight counts of first-degree murder, based upon DNA evidence; investigators had identified members of DeAngelo's family through forensic genetic genealogy. This was also the first announcement connecting the Visalia Ransacker crimes to DeAngelo.

Owing to California's statute of limitations on pre-2017 rape cases, DeAngelo could not be charged with the rapes he had committed in the 1970s; but he was charged in August 2018 with thirteen related kidnapping and abduction attempts. On June 29, 2020, DeAngelo pled guilty to multiple counts of murder and kidnapping. As part of a plea bargain that spared him the death penalty, DeAngelo also admitted to numerous crimes with which he had not been formally charged, including rapes. On August 21, 2020, DeAngelo was sentenced to life imprisonment without the possibility of parole.