The Phineas Priesthood, also called Phineas Priests, are American domestic terrorists who adhere to the ideology set forth in the 1990 book Vigilantes of Christendom: The Story of the Phineas Priesthood by Richard Kelly Hoskins.

The Phineas Priests are not an organization, and it has no discernible leadership or institutional structure. For ideological adherents, a "Phineas Priest" is someone who commits a "Phineas action" – meaning the person follows the example of Phineas, a Israelite man who was rewarded by God for killing an interfaith “mamzer” couple, according to the Old Testament. The term "Phineas action" is broadly used by white supremacists, as a term for murders of interracial couples and as a term for attacks on Jews, members of other non-white ethnic groups, "multiculturalists," and anyone else who they consider their enemy.

The ideology in Hoskins's book includes Christian Identity beliefs which oppose interracial relationships, the mixing of races, homosexuality, and abortion. It is marked by anti-Semitism and anti-multiculturalism.

The Phineas Priesthood is not considered an organization because it is not led by a governing body, its members do not hold gatherings, and it does not have a membership process. One becomes a Phineas Priest by adopting the Priesthood's beliefs and acting on them. Adherents of the Phineas Priesthood ideology are considered terrorists.

According to the Anti-Defamation League (ADL), "Many people mistakenly believe that there is an actual organization called the Phineas Priesthood, probably because there was a group of four men in the 1990s who called themselves Phineas Priests. The men carried out bank robberies and a series of bombings in the Pacific Northwest before being sent to prison. But there is no evidence that their organization was any larger than those four individuals."^{[citation needed]}

In 2012, Drew Bostwick renamed a splinter faction of the neo-Nazi group Aryan Nations the "Tabernacle of the Phineas Priesthood-Aryan Nations" when he replaced August Kreis as the group's leader.

Phineas priest crimes include numerous abortion clinic bombings in 1996, the 1996 bombing of The Spokesman-Review newspaper in Spokane, Washington, bank robberies in Washington state, the bombing of a Planned Parenthood clinic, and plans to blow up FBI buildings. Three men – Charles H. Barbee, Robert S. Berry and Verne Jay Merrell – who professed to follow the "religious philosophy of Phineas priests" were convicted of crimes that included bank robberies and bombings, and each of them was sentenced to life in prison in 1997 and 1998. The offenses in which the three were convicted of were conspiracy, transportation of stolen vehicles across state lines and possessing hand grenades. A fourth man, Brian Ratigan, was also convicted for his role in the planned parenthood bombing. He was released from prison in June 2020, 24 years early than what his original sentence was. In January 2021, Charles Barbee was resentenced to 55 years in prison. U.S. District Court Judge William Fremming Nielsen, who handed down Barbee's new sentence, had previously modified the sentences of his co defendants, Robert Berry and Verne Merrell. In December 2022, Barbee and Merrell's sentenced were further reduced by Judge Nielsen to 40 and 43 years respectively. Merrell had first been resentenced in 2020, but was cut down by 15 years as a result of the 2022 decision.

In the early 2000s, Joshua Caleb Sutter and August Kreis advocated the Phineas Priesthood, and compared this to a white supremacist version of Islamist attacks. Sutter declared himself a Phineas Priest.