In an interview with Eurogamer, O'Connor explained that despite the fact that the novels do a pretty solid job of fleshing out exactly how Spartan 117 looks, they're "not ready to show the Master Chief's face."
The funny thing about the Chief is he’s actually really well-described. If you went down into that line and found a nerd with a deep cannon Halo t-shirt and said describe the Master Chief to this police sketch artist, that police sketch artist would then produce a perfectly accurate rendering of an older man, almost painfully pale, almost albino white, with pale blue eyes, reddish hair, close cropped to a skin head, and maybe the last remnants of freckles he had when he was a kid.
The conversation then took a dark turn, when O'Connor was asked about the possibility of killing off the iconic hero. “That’s a conversation I can’t get into," he replied. "I’ll say that in Halo 4, things happen. Previously we’ve been scared to commit to difficult paths in our game, but good interesting stories have things that happen in them that are not comfortable and that are meaningful and that are permanent.
“I’m not trying to hint at something other than our general philosophy and the shift in the attitude we’re taking about storytelling. We can make the story matter more to people by doing things that matter.”
Halo 4 launches on November 6th for Xbox 360.