Joseph James DeAngelo Jr. (born November 8, 1945) is an American serial killer, sex offender, burglar, and former police officer who committed at least 13 murders, 51 rapes, and 120 burglaries across California between 1974 and 1986. He is responsible for at least three separate crime sprees throughout the state, each of which spawned a different nickname in the press, before it became evident that they were committed by the same person.

In the San Joaquin Valley, DeAngelo was known as the Visalia Ransacker before moving to the Sacramento area, where he became known as the East Area Rapist and was linked by modus operandi to additional attacks in Stockton, Modesto and Contra Costa County. DeAngelo committed serial murders in Santa Barbara, Ventura, and Orange counties, where he was known as the Night Stalker and later the Original Night Stalker (owing the former moniker to serial killer Richard Ramirez, also being called the "Night Stalker"). He is believed to have taunted and threatened both victims and police in 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, after DNA testing indicated that the East Area Rapist and the Original Night Stalker were the same person, the combined acronym EARONS came into use. 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. To heighten awareness of the case, crime writer Michelle McNamara coined the name Golden State Killer in early 2013.

On June 15, 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, the State of California 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 1970s rapes; 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.