Project X could refer to:
- Project X (film), a 1987 film starring Matthew Broderick.
- Project X (web serial), is a 24-episode web series and feature film.
- Project X (Comedy Shorts) short lengthed comedy series Written by and Starring Dale Thompson and Trevor White
- Project X (band), a late 1980s New York City hardcore punk band.
- Project-X, a horizontally-scrolling shoot 'em up computer game for the Amiga, released by Team17 in 1992.
- Project X (TV show), a popular Japanese television show about projects such as the creation of cup noodles, engineering of bridges or developing the Sony Walkman.
- A military project by Nazi Germany's Aviation Ministry to develop a rocket-powered interceptor aircraft. The project would result in the design and manufacture of the Messerschmitt Me 163.
- A United States political scandal involving controversial technology administrator Laura Callahan, who allegedly threatened subordinates with jail if they did not conceal computer problems leading to the disappearance of thousands of subpoenaed White House emails.
- Project X, a code-name for the Manhattan Project specifically pertaining to the Oak Ridge National Laboratory Program.
- Army Foreign Intelligence Assistance Program, also called Project X which supplied training materials and taught torture to allied militaries around the world. The declassified U.S. Army and CIA interrogation manuals were developed from these manuals.
- Project X, a retail package sold by radio station WNNX-FM (99X) in Atlanta.
- The Apple HotSauce software was called Project X in early stages of its development.
- An earlier name for the now defunct Nuon platform that added extra features to DVD titles.
