Holy Shit! I Found It!:
I've long said that I began my comics reading with G.I. Joe and Uncanny X-Men, and that is true... those were the first comics I bought for myself, or had my parents buy at convenience stores, etc.
But the first book I remember reading, back in my hazy younger days, was some Superman/Hawkman team-up featuring Dr. Polaris. I had no idea what issue it was, or what comic, and I only remember that my parents bought it for me on a car trip. And then... I tuned into Will Pfeifer's guest entry on Comics Should Be Good and, if I'm reading this right, it was also the first comic that Pfeifer bought for himself. So here it is, the first comic I can ever remember reading:
I have almost no recollection of the interiors, and I don't doubt Pfeifer's estimation of it (lame), but... it was cool to see it again.