Bartolomé de las Casas, OP was a Spanish clergyman, writer, and activist best known for his work as a historian and social reformer. He arrived in Hispaniola as a layman, then became a Dominican friar. He was appointed as the first resident Bishop of Chiapas, and the first officially appointed "Protector of the Indians". His extensive writings, the most famous being A Short Account of the Destruction of the Indies and Historia de Las Indias, chronicle the first decades of colonization of the West Indies. He described the atrocities committed by the colonizers against the indigenous peoples.

The Order of Preachers, also known as the Dominican Order, is a Catholic mendicant order of pontifical right that was founded in France by a Castilian priest named Dominic de Guzmán. It was approved by Pope Honorius III via the papal bull Religiosam vitam on 22 December 1216. Members of the order, who are referred to as Dominicans, generally display the letters OP after their names, standing for Ordinis Praedicatorum, meaning 'of the Order of Preachers'. Membership in the order includes friars, nuns, active sisters, and lay or secular Dominicans. More recently, there has been a growing number of associates of the religious sisters who are unrelated to the tertiaries.