- Family: Atlas
- Length: 20.27 m
- Diameter: 3.05 m
- Launch Mass: 130 T
The Atlas LV-3 Agena B was manufactured by United States Air Force with the first launch on 1961-01-31. Atlas LV-3 Agena B has 21 successful launches and 8 failed launches with a total of 29 launches. The Atlas LV-3A was a largely unsuccessful configuration until it was given an Agena B upper stage. It was responsible for the launch of Mariner II to Venus and had one of the first engines that could be restarted in orbit.