Amgen Inc. is an American multinational biopharmaceutical company headquartered in Thousand Oaks, California. One of the world's largest independent biotechnology companies, Amgen's Thousand Oaks staff in 2022 numbered approximately 5,000 and included hundreds of scientists, making Amgen the largest employer in Ventura County. As of 2022, Amgen has approximately 24,000 staff in total.

Thousand Oaks is the second-largest city in Ventura County, California, located in the northwestern part of Greater Los Angeles. Approximately 15 miles (24 km) from the city of Los Angeles and 40 miles (64 km) from Downtown Los Angeles, it is named after the many oak trees present in the area.