These are getting some support from the creators of Tanya The Evil (both light novel series are published by Kadokawa’s Enterbrain).
In a message published on Overlord’s anime site, Tanya The Evil’s Carlo Zen explains that he has been a fan of Overlord since Maruyama Kugane was publishing it as a web novel (which lacked Albedo, among other fan favorites).
The Undead King hits Japanese theaters on February 25, 2017, followed by The Dark Warrior on March 11th.