Guillermo del Toro's upcoming animated series Trollhunters has assembled an ace voice cast, which would seem to indicate that it's actually happening. They've been working on this one for a while, but I never trust del Toro projects until they're on my screen in front of me.
The three big names that have joined the cast are Ron Perlman (of course), Kelsey Grammer, and Anton Yelchin (who will also be joining the cast of the upcoming Mr. Mercedes series).
Originally intended as a feature film, then released as an illustrated novel by del Toro and Daniel Kraus in 2015, the series takes place in:
the fictional suburb of Arcadia, our unlikely hero, Jim, and his two best friends make a startling discovery that beneath their hometown lies a hidden battle between good trolls and bad, the outcome of which will impact their lives forever.
Yelchin will play Jim, "an ordinary teenage boy whose discovery of a mystical amulet sets his life on a course filled with high-stakes adventure." Kelsey Grammer is Blinky, "a kind-hearted troll who befriends Jim." Ron Perlman, naturally, voices Bular, "a sinister troll who targets Jim and his friends for battle."
Trollhunters will premiere this December on Netflix.