Sunday is Monkey Covers day here at YACB. Because there's nothing better than a comic with a monkey on the cover!
Detective Chimp helps Batman and Elongated Man find a missing Gorilla City on the cover of Justice League Unlimited #39 (2008) by Zach Howard.
(Standard disclaimer about detecting chimpanzees not really being monkeys applies.)
Image courtesy of the GCD. Click on the image for a larger version.