Avengers (1963-1996) #1.5

"The Death-Trap of Doctor Doom!"
The Mighty Thor! The Invincible Iron Man! The Incredible Hulk! The Astonishing Ant-Man and the Wonderful Wasp! They are the Avengers! And, in this issue, a startling new hero joins their ranks! Who is he? That would be telling. (Hey, we have to save some surprises for the story!) Plus: a couple of don't-blink-or-you'll-miss-'em guest-appearances by the Fantastic Four and the Amazing Spider-Man!