astronauts had flown on Gemini, and except for White, each commanded one Gemini and one Apollo mission:

Edward H. White II - Second-seat veteran of Gemini 4 who made the United States' first walk in space, selected as Senior Pilot (second seat) on Apollo 1. White was killed with Grissom and Chaffee in the fire.

James A. McDivitt – Commander of Gemini 4, selected in late 1966 to command the first Earth orbital flight test of the Apollo Lunar Module with the CSM. This mission flew in March 1969 as Apollo 9. After his flight, McDivitt was promoted to Manager of Lunar Landing Operations, and in August 1969 was promoted to Manager of the Apollo Spacecraft Program.

Frank F. Borman II – Commander of Gemini 7, selected to command a higherEarth orbit test of the complete Apollo spacecraft. But when delays prevented the LM from being ready in time for its first flight in December 1968, Borman's mission was changed to the first lunar orbital flight of the CSM on Apollo 8.

James A. Lovell, Jr. – Second-seat veteran of Gemini 7, and commander of Gemini 12, flew as Command Module Pilot (second seat) on Apollo 8. Lovell became the first to fly a second Apollo mission as commander of Apollo 13, the third lunar landing attempt. This mission was unsuccessful, due to a Service Module electrical system failure caused by the explosion of an oxygen tank. Lovell and his crew managed to return to Earth safely.

John W. Young – Second-seat veteran of Gemini 3 and commander of Gemini