Spanish missionaries were religious individuals sent by the Spanish Crown and the Catholic Church to spread Christianity in the Americas during the 16th to 19th centuries. They established missions, which were communities aimed at converting Indigenous peoples to Christianity and teaching them European customs and agriculture. These missionaries played a significant role in the colonization process, often working alongside explorers and settlers. Notable figures include Junípero Serra, who founded several missions in California. While they aimed to promote faith, their efforts also led to significant cultural changes and conflicts with Indigenous populations.