Gundam is the father of the "big robot" style of Japanese animation.  Gundam began in 1979 with MS Gundam.  This was the landmark series that started all the others.  Gundam can be watched on Cartoon Network on Saturdays at 12:30 AM on Adult Swim.  This website has information on Gundam Wing, Gundam 0083: Stardust Memories, and G-Gundam.