Thousand Oaks is the second-largest city in Ventura County, California, United States. It is in the northwestern part of Greater Los Angeles, approximately 40 miles (64 km) from Downtown Los Angeles, and is less than 15 miles (24 km) from the Los Angeles neighborhood of Woodland Hills. It is named after the many oak trees present in the area.
The city forms the central populated core of the Conejo Valley. Thousand Oaks was incorporated in 1964, but has since expanded to the west and east. Two-thirds of neighboring Westlake Village and most of Newbury Park were annexed by the city during the late 1960s and 1970s. The Los Angeles County–Ventura County line crosses at the city's eastern border with Westlake Village. The population was estimated to be 126,813 in 2019, up from 126,683 at the 2010 census.