Mine was Naruto;)

Mine was Ronin Warriors. Came on Fox after Dinosaurs (the Muppet one) and before Samurai Pizza Cats. I think I was eight or nine.

Dragonball Z was my first anime I began watching on toonami
either on a weekly or daily basis my memory fails me.

Since then I have just been going from anime's like DBZ to DB,Dr Slump etc..

Also Samarai Jack is up there on the list due to it airing after DBZ-DBGT each Night/Week.

Ronin Warriors was the first one I ever watched, but the one that actually got me into anime at all was probably DBZ.  Or maybe Ghost in the Shell.  I think Excel Saga was also one of the first ones I ever watched.

My gateway series was Pokemon Season 1 on Kids WB. I wasn't exposed to Toonami until 2001-2002.

Like most of you, I grew up getting my first taste of anime through Toonami, watching shows that really captivated me such as Dragon Ball, Dragon Ball Z, Yu Yu Hakusho, and many, many more. 

However, the show that really changed my outlook on anime and REALLY pulled me into loving it to this very day has to be Case Closed. Some may call the show repetitive and over-long, but I don't care. For me, it's a timeless show and the formula of every episode will never ever become dull. Every single time I take a moment to watch one of the dubbed episodes or films, I'm completely attached to every second of it. Unfortunately, its popularity definitely was completely different in the United States compared to Japan (just to state the obvious, seeing as how the anime stopped being dubbed years ago and it's still on-going with over 600 episodes in Japan). I've been crossing my fingers and simply hoping that one day it'll be given a second chance in the United States, because despite having around 130 episodes dubbed here, nobody should miss out on such a creative and classic show. Maybe I'll just finally cave and watch the episodes subbed, but you never know. Until then, I'm stuck re-watching the nostalgic classic of my childhood and hope that as many people as possible will stumble upon it sooner or later as well. I highly recommend it. 

Salior Moon

No words Necessary my friends

Also the original Japanese version of Sailor Moon and The early Gundam shows got me hooked too.

tbh I dont remember which anime was my first, I got my exposure thanks to SciFi channel back in the early 90s , it showed alot of stuff like Akira, Tekkaman Blade, Vampire Hunter D, Casshern, 8Man(i think that's what it was called), Venus Wars, Tenchi Muyo in Love, you could say any of the above was my first, then there was a few DBZ episodes I caught on Fox as well as Rurouni Kenshin I saw on a local channel, Bubblegum Crisis and Ghost in the Shell on Starz but I really didnt get back into anime until Toonami came around, everyday I rushed home from school to catch GW, Outlaw Star and Yu Yu Hakusho....the memories.......

Jaycee and the wheeled warriors., il'd say, was a very fine line with 80's cartoons and anime in my opinion.