Chris Bilheimer has been the creative force behind the artwork for every Green Day album since 1997's Niimrod. He's created some of the most recognizable Green Day logos -- the "heart-grenade," the kissing couple on the front of 21st Century Breakdown, and the Warning shock-man, to name a few. In addition to his work with Green Day, he has also contributed artwork designs to numerous other bands, such as R.E.M., Widespread Panic, All-American Rejects, O.A.R., and Neutral Milk Hotel.

Lately, Bilheimer has been doing some design work for the fashion industry. You can read more about what he's been up to lately in this interview. Here's a very interesting Green Day-related tidbit we get from this article:

You should check out some artwork by Saul Bass, to see the style that inspired the design.

Thanks to @GDLot for tweeting this story.