Joseph M. Arpaio (born June 14, 1932 in Springfield, Massachusetts, United States) is a law enforcement officer, and the sheriff of Maricopa County, Arizona. Arpaio, who promotes himself as "America's Toughest Sheriff," is controversial for his approach to operating the Maricopa County Sheriff's Office. He has a large number of vocal supporters as well as detractors. His practices have been criticized by organizations such as Amnesty International, the American Civil Liberties Union, the Arizona Ecumenical Council, the American Jewish Committee, and the Arizona chapter of the Anti-Defamation League.

Arpaio continues to enjoy the support of Maricopa County voters, who reelected him sheriff by double-digit margins in 1996, 2000, 2004 and 2008. In 2007 a petition to recall Arpaio from office failed to gain enough voter signatures to get on the ballot. In a survey taken by the Walter Cronkite School of Journalism and Mass Communication while the petition was in circulation, nearly three out of four respondents opposed the recall, and 65 percent of the respondents held a positive opinion of Arpaio.

Arpaio is of Italian heritage. His mother died while giving birth to him, and Arpaio was raised by his father, a grocery store owner. He completed high school and worked in his father's business until age 18 when he enlisted in the United States Army.