Father Fermín Francisco de Lasuén (June 7, 1736 – June 26, 1803) was a Spanish missionary to the Americas.

He was born in Vitoria and joined the Franciscan order, becoming ordained in 1752. In 1758 he volunteered to work in America. He arrived in Mexico in 1761 and was sent to Baja California in 1768. Following the establishment of the mission at San Diego in 1769, he went to Northern California in 1773. He was never happy in California. He based himself in San Diego and remained there until 1775, he helped establish the mission at San Juan Capistrano before the murder of Father Luis Jayme and Kumeyaay Indian unrest caused his return to San Diego and the general withdrawal of Spanish operations. In late 1776 he went to San Luis Obispo before again returning to San Diego in 1777 when he was made minister there. He was made the second Presidente of the missions in California in 1785, replacing Junipero Serra, and transferred to the Carmel Mission. On his death he was succeeded by Estevan Tapis .

He personally established nine of the twenty-one "Alta California" missions:

• Mission Santa Barbara (1786)
• Mission La Purisima Concepcion (1787)
• Mission Santa Cruz (1791)
• Mission Nuestra Senora de la Soledad (1791)
• Mission San Jose de Guadalupe (1797)
• Mission San Juan Bautista (1797)
• Mission San Miguel Arcangel (1797)
• Mission San Fernando Rey de Espana (1797)
• Mission San Luis Rey de Francia (1798)

He also oversaw the expansion of many of the sites.