Invaders King-Size Annual #1 from Marvel Comics
While the cover is nothing special, this is the first super-hero comic book that I ever bought.  I remember buying it at 7-11 and instantly became hooked on super heroes, especially Marvel heroes.  To go from funny animal comic to reading about the Human Torch, Submariner and Captain America just overwhelmed me. 

       

This is a scan of an old comic book. This item is not for sale. But you can find it on ebay.
Click below to go to ebay and search!