Leonard Peltier (born September 12, 1944) is a Native American activist and a member of the American Indian Movement (AIM) who, following a controversial trial, was convicted of two counts of first-degree murder in the deaths of two Federal Bureau of Investigation (FBI) agents in a June 26, 1975, shooting on the Pine Ridge Indian Reservation in South Dakota. He was sentenced to two consecutive terms of life imprisonment and has been imprisoned since 1977 (currently 45 years, 11 months). Peltier became eligible for parole in 1993. As of 2022, Peltier is incarcerated at the United States Penitentiary, Coleman in Florida.

In his 1999 memoir Prison Writings: My Life Is My Sun Dance, Peltier admitted to participating in the shootout but said he did not kill the FBI agents. Human rights watchdogs, such as Amnesty International, and political figures including Nelson Mandela, Mother Teresa, and the 14th Dalai Lama, have campaigned for clemency for Peltier. On January 18, 2017, it was announced that President Barack Obama denied Peltier's application for clemency.

At the time of the shootout, Peltier was an active member of the AIM, an Indigenous rights advocacy group that worked to combat the racism and police brutality experienced by American Indians. Peltier ran for president of the United States in 2004, winning the nomination of the Peace and Freedom Party, and receiving 27,607 votes, limited to the ballot in California. He ran for vice president of the United States in 2020 on the Party for Socialism and Liberation ticket with Gloria La Riva as the presidential candidate, as well on tickets for other Left parties and on the ballot of the Peace and Freedom Party. For health reasons, Peltier withdrew from those tickets on August 1, 2020.

He is of Lakota, Dakota, and French descent, and is an enrolled member of the Turtle Mountain Chippewa.