Clifton 'C.C.' Williams (September 26, 1932 - October 5, 1967) was a NASA astronaut and USMC Major who was killed after a mechanical failure caused the flight controls in a T-38 he was piloting to stop responding. The aircraft crashed in Florida near Tallahassee.

He had previously served on the backup crew for Gemini X and had been assigned to the back-up crew for what would be the Apollo 9 mission. This crew placement would have most likely lead to an assignment as Lunar Module pilot for Apollo 12. After his death he was replaced on the Apollo 9 backup crew by Al Bean who had been his commander on the Gemini X backup crew.

The Apollo 12 mission patch has four stars on it - one each for the three astronauts who flew the mission, and one for Williams.