Super Secret Crisis War! The Grim Adventures of Billy and Mandy One-Shot — IDW Publishing
Issue: #1
A malfunctioning robot crash-lands in Billy and Mandy’s school! Billy wants to keep it, Mandy wants it out, and Grim is just confused. As the robot starts causing havoc, it’s up to our heroes (and Billy) to put an end to the mayhem!
First appearances: Eleanor Butterbean
Creators: Louise Jones Simonson, Carlos Guzman, Tom B. Long, Troy Little, Sarah Gaydos, Maxwell Atoms, Kate Leth, Ethen Beavers, Derek Charm
Characters: Aku, Bubbles, Blossom, Mojo Jojo, Mandy, Death, Dexter, Samurai Jack, Mandark, Ben 10, Buttercup, Billy, Eleanor Butterbean
Story arcs: Super Secret Crisis War!