According to Find A Grave, a website through which contributors provide records from cemeteries around the world, there are 2.7 million memorialized (marked) gravesites recorded in Los Angeles County. Among these are the earliest known burials in the county, reported to be interred at the San Gabriel Mission Cemetery (the county's oldest cemetery):
The village Sibapet was reported to be the indigenous community (possibly the neophytes or Indian converts) at the San Gabriel Mission. Ajuibit was a native village once located in what is now the La Puente area. Thomas was baptized as an infant at the mission, less than a year before his death. Monica Maria was also baptized there as an adult, just a little more than a month before her burial. She was also recorded as single at the end of her life. No baptismal record was found for Pascual Maria. The only names we know these three people by were the Spanish names assigned by the Spanish missionaries. Their original Indian names, along with their culture, were erased. We know nothing more than that they were among the earliest indigenous converts brought into the mission community. Their burials were the earliest recorded in Los Angeles County, just three years after the establishment of the San Gabriel Mission and seven years before the settlement of El Pueblo de la Reina de Los Angeles.
The Almanac was unsuccessful at trying to find the specific locations for these gravesites on the San Gabriel Mission property. The Mission Rectory explained that mission burial site records earlier than the 20th century are limited or non-existent. As it turned out (and we should have known this), in 1774, the San Gabriel Mission was actually located at its original site near Whittier Narrows. Due to frequent flooding, in 1775, the mission was moved from that site to where it is now located. The three earliest recorded gravesites would have been at the original mission site. Unfortunately, there remains no record of what happened to burials at the original mission site and whether the remains were moved to the new site. This leaves us with no way of knowing where, exactly, L.A. County's three earliest recorded burials are at rest.
Sources:
-- Find A Grave
-- Early California Population Project Database
-- Almanac research
Also see: La Brea Woman - L.A.'s Earliest Known Human Resident.