Gundam 0

Gundam 0 was the mobile suit that saved Setsuna F. Seiei's life in 2305 AD. From its name and introduction, it may be the prototype for the other Gundams used by the Celestial Being.

Trivia
Gundam 0 bears a striking resemblance to the RX-78-2 Gundam of the Universal Century with a GN Drive tacked on.