Williams International is an American manufacturer of small gas turbine engines based in Pontiac, Michigan, United States.

It has been building small turbofan engines since the 1950s for use in cruise missiles as well as target and reconnaissance drones.

Using the missile engines, Williams developed a series of personal VTOL flying craft, including a jet-powered belt in 1969, the Williams Aerial Systems Platform (WASP), also known as the "flying pulpit" in the 1970s, and the X-Jet, which was evaluated by the United States Army in the 1980s.

The company introduced the FJ44 engine, which in turn made possible the introduction of a number of small jet aircraft.

In 1996, Williams joined AGATE's General Aviation Propulsion program to develop a fuel-efficient turbofan engine that would be even smaller than the FJ44.