Sunday is Monkey Covers day here at YACB. Because there's nothing better than a comic with a monkey on the cover.
Joe Kubert draws the Challengers being chased off an island by a giant ape-beast on the cover of Challengers of the Unknown #79.
(Standard disclaimer about giant ape-beasts not really being monkeys applies.)
Image courtesy of the GCD. Click on the image for a larger version.