The X-Men #34

Titled "War — In a World of Darkness!", this July 1967 Marvel issue throws the X-Men headlong against a towering armored giant, with Cyclops's optic blast exploding against its massive frame while Iceman, Beast, and a winged figure dart into the fray — and a mysterious caped warrior in golden armor squares off from the left. Hovering above it all, a stern bald face crackles with psychic energy, and the upper corner reminds us the whole team is ready for battle. Dan Adkins handles both pencils and inks on a cover that crackles with the bold, energetic style that made late-1960s Marvel so appealing.