Well I used to always watch Toonami when I was younger and the first one I saw is hard to tell since I saw so many. The first one I really got into was Naruto and I watched it every week. I also saw some Gundam, Full Metal Achemist, Cowboy Bebop, Prince of Tennis, Bobabo, and some weird hamster show. Seriously does anyone remeber an anime about hamster's adventures in some back yard. I loved the action in them, when your a kid Dragon Ball Z is the greatest thing ever. I did have some moments where I wondered "What is happening?" in the more mature moments.