The first settlers of Bacolor were believed to be Malays that came from Atjeh in Sumatra led by Panday Pira. It is believed to have been founded by Monmon, first cousin and sister-in-law of Malangsic, a son of Prince Balagtas. However, historians recorded the official foundation of Bacolor in 1574 through a landlord named Guillermo Manabat, whose palatial house and resting place is now the site of the San Guillermo Church, hence the church's name. The name Bakúlud was changed to "Bacólor" with the advent of the Spanish.