Spanish missionary and historian Bartolomé de las Casas sought to abolish the oppression and enslavement of the native peoples in the Americas.

This member of order of preachers, a 16th-century social reformer and Dominican friar, served as the first resident bishop of Chiapas and the first officially appointed "protector of the Indians." The most famous A Short Account of the Destruction of the Indies and Historia de Las Indias of his extensive writings chronicle the first decades of colonization of the west and focus particularly on the atrocities that the colonizers committed against the indigenous.

In 1515, he reformed his views, gave up his encomienda, and advocated before Charles V, king and holy Roman emperor, on behalf of rights. In his early writings, he advocated the use of Africans instead in the West Indian colonies; consequently, people leveled criticisms as partly responsible for the beginning of the transatlantic trade. Later in life, he retracted those early views and came to see all equally wrong forms. In 1522, he attempted to launch a new kind of peaceful colonialism on the coast of Venezuela, but this venture failed, causing las Casas to enter the Dominican order as a friar and to leave the public scene for a decade. He then traveled to central to undertake peaceful evangelization among the Maya of Guatemala and participated in debates among the Mexican churchmen about best to bring to the Christian faith. He traveled back to recruit and continued lobbying against the encomienda, gaining an important victory by the passing of the New Laws in 1542. He was appointed bishop of Chiapas, but served only for a short time before he was forced to return because the encomenderos resisted the new laws, and conflicts with settlers because of his pro-Indian policies and activist religious stances. The remainder of his life was spent at the court where he held great influence over Indies-related issues. In 1550 he participated in the Valladolid debate; he argued against Juan Ginés de Sepúlveda that the Indians were fully human and that forcefully subjugating them was unjustifiable. Sepúlveda countered that they were less than human and required masters in order to become civilized.

Bartolomé de las Casas spent 50 years of his life actively fighting and the violent colonial abuse of indigenous, especially by trying to convince the court to adopt a more humane policy of colonization. His efforts resulted in several improvements in the legal status, and in an increased colonial focus on the ethics of colonialism. Las Casas is often seen as one of the first advocates for universal Human Rights