Or so we are told, anyway:
OK, look, Microsoft isn't so stupid as to kill off the iconic face of its most important, lucrative, and powerful revenue-generating franchise and brand. I have no doubt that this is part of the HALO 5 plotline; I also have no doubt, based on what I already know, that the Master Chief isn't actually dead.
After all, they kind of sort of killed him off before. Yes, I know, technically he was "Missing In Action", like all SPARTANs are supposed to be. But as far as everyone in the HALOverse was concerned, he was dead. Until he wasn't. Again.
Still, a small part of this die-hard HALO nut's mind did do a backwards-flip when I saw that TV spot. It looked something like this: