Halo is getting the cartoon treatment with Halo: The Fall of Reach. Taken from their officialYoutube post:
"This three act series tells the oft-shrouded origin stories of the Spartan-II program. Set during events both befroe and after the terrifying Covenant attack on humanity, the story will introduce viewers to the members of Blue Team and allow them to witness pivotal moments that forged the legendary squad's legacy."
Halo getting the animated treatment should make for a fantastic show, as the Halo 4 Spartan Ops movies were a joy to watch. The show is an animated adapatation of Eric Nylund's novel, showing the origin of Master Chief.
The animated series will be included in the Digital Deluxe Edition, Limited Edition, and Limited Collector's Edition of Halo 5: Guardians on October 27th.