John D. Carmack II (born August 21, 1970) is an American computer programmer and video game developer. He co-founded the video game company id Software and was the lead programmer of its 1990s games Commander Keen, Wolfenstein 3D, Doom, Quake, and their sequels. Carmack made innovations in 3D computer graphics, such as his Carmack's Reverse algorithm for shadow volumes.

In 2013, he resigned from id Software to work full-time at Oculus VR as their CTO. In 2019, he reduced his role to Consulting CTO so he could allocate more time toward artificial general intelligence (AGI). In 2022, he left Oculus to work on his AGI startup, Keen Technologies.