Source: http://www.ign.com/articles/2014/07...o-5-guardians?abthid=53d15d6f3aec96de28000011IGN said:Agent Locke, the star of Ridley Scott's Halo: Nightfall, is a playable character in Halo 5: Guardians, 343 Industries revealed today during an SDCC panel.
Nightfall is the origin story for Jameson Locke, which leads into his role in Halo 5. Set on a broken piece of the Halo ring from Halo: Combat Evolved, this is the story of Locke growing into a Spartan. 343's Frank O'Connor described Locke's story as "a superhero origin story" that's more closely integrated to Guardians than Forward Unto Dawn was with Halo 4.
From FB - panel starts now it seems.