Diablo and Overwatch are both getting animated series based on them, and the Diablo series will be an anime-style show for Netflix, much like Castlevania. This is according to the LinkedIn profile of Nick van Dyk, co-president of Activision Blizzard Studios, who previously served as a producer on the Netflix original animated series Skylanders Academy.
According to van Dyk's description of his position within Activision, Diablo is getting an animated adaptation "rendered in anime style," which is currently in pre-production and will release worldwide through Netflix. This series has been rumored for some time, but this seems like confirmation that it is happening--although it could be a while away yet if it's still in pre-production.
Further down, van Dyk mentions that he "developed and sold an animated series based on Blizzard's Overwatch franchise," alongside his creative partner. Nothing formal has been announced about this series, and it's not clear who the series has been sold to. Overwatch has frequently fleshed out its backstory with CGI animated shorts, including the Overwatch 2 announcement cinematic.
We've contacted a representative for Activision requesting clarification, and will update this post if and when we receive further information.
Activision is also working on a Call of Duty movie, although it's just been announced that it has been put on hold. Several movies are planned, with a Call of Duty cinematic universe of sorts being built, with the first to be directed by Stefano Sollima (Sicario: Day of the Soldado). Joker writer Scott Silver was brought in to co-author the film's script.