The Grim Adventures of Invader Zim

 is an American animated science fiction-supernatural-comedy television film serving as a crossover between ' and ', being co-directed by and Maxwell Atoms. It is produced by Cartoon Network Studios, Warner Bros. Animation and Nickelodeon Animation Studios and it will premiere on on March-August TBDth, 2021.

Summary
As another tentative to take over the Earth, Zim discovers a portal that allows him to find another dimension where an entity known for working for TBD is tired of its life and TBD.

Voice cast

 * Richard Steven Horvitz as:
 * Zim, TBD
 * Billy, TBD
 * Harold, TBD
 * as GIR, TBD
 * Grey Griffin as Mandy, TBD
 * Greg Eagles as the Grim Reaper, TBD
 * Andy Berman as Dib Membrane, TBD
 * Melissa Fahn as Gaz Membrane, TBD
 * Vanessa Marshall as Irwin, TBD
 * [supporting to Zim besides Prof. Membrane]
 * Jennifer Hale as Gladys, TBD
 * Diedrich Bader as Hoss Delgado, TBD
 * Phil LaMarr as Cound Dracula, TBD
 * C.H. Greenblatt as Fred Fredburger, TBD

Trivia

 * This is the third crossover between a Warner Bros. and a Nickelodeon property, with the first and second being Velocity and Samurai Jack: Demon's Edge and Batman vs. the TMNT