UFO Robo Grendizer, known alternately by the names Grandizer, Goldorak and Goldrake, was the final series of the Mazinger trilogy, and one of the most well-received.
Grendizer is about a young prince of the Royal Family of Fleed, whose planet is turned into a radioactive wasteland by the invading army of the Vegan Alliance. The Vegans had invaded to steal the planet for themselves, as their own had slowly fell into ruin as well. After this tragedy, the young prince, Duke Fleed, managed to hijack the Vegan Alliance's prize UFO Robo - the Grendizer. Fleeing, he crash lands on Earth, two years ahead of the pursuing Vegan Army. There he is taken in by a kindly scientist named Dr. Umon. When the Vegans (*snicker* ) attack, Duke takes the Grendizer into battle, along with Kouji Kabuto, the pilot of Mazinger Z.
When it was shown in the US, it was changed into Grandizer as part of the Force Five syndication block. Two episodes of Grandizer were released on VHS in America; it is otherwise hard to get in the US.