The Agena launch vehicle has been an integral part of both unmanned and manned space programs. Flown as an upper stage on Thor and Atlas boosters, Agena orbited an impressive roster of spacecraft including the Echo communications satellites, the Ranger and Lunar Orbiter Moon probes, and the Mariner vehicles that traveled to Venus and Mars.

As the target for docking experiments during Project Gemini, Agena made substantial contributions to the eventual success of the Apollo program. The vehicle earned the distinction of being the first to place a payload in polar orbit, and was also the first to achieve circular orbit. The Agena engine was the first which could be stopped and restarted in space.

The Agena launch vehicle was developed and manufactured by the Lockheed Missiles and Space Company for the United States Air Force.

The Agena-B is from the United States Air Force and the Lockheed Missile and Space Company.