General William J. Fox Airfield (IATA: WJF, ICAO: KWJF, FAA LID: WJF) is a county-owned, public airport in Los Angeles County, California, five miles northwest of Lancaster, California, United States. Locally known as Fox Field, the airport serves the Antelope Valley. The airport is named after Brigadier General William J. Fox, "a Marine war hero, a movie stunt man, the first Los Angeles County engineer and, for 20 years after his retirement, a cowboy."

The National Plan of Integrated Airport Systems for 2011–2015 categorized it as a general aviation facility. The airport has limited scheduled cargo operations. The U.S. Forest Service has a fixed wing airtanker and helicopter base on the airfield which becomes one of the main hubs in the region for aerial firefighting suppression efforts during fire season.