FCAS may refer to:
Familial cold autoinflammatory syndrome, a genetic disease Fellow of the Casualty Actuarial Society, a U.S. professional society The Foundation to Combat Antisemitism, a philanthropic effort by Robert Kraft Frequency Control Ancillary Services for electric power grids Future Combat Air System, a former sixth-generation fighter jet previously developed by France, Germany, and Spain, cancelled in 2026 Future Combat Air System (UK), a sixth-generation fighter jet, the BAE Systems Tempest, and related technologies currently under development by the United Kingdom, Italy and Sweden. FCA Serbia, a car manufacturer