^Okay, so he might
be someone whose name begins with M. Although the article goes on to say that it may have just been a "hmm" sound. And it adds:
The executive producer went on to say that the character may "not necessarily" be familiar to those who read Marvel comics.
"We’re going to draw from it, but Marvel has its thing, and we’re also going to be expanding forward, and this world is different since 'The Avengers,'" Bell said. "So I think there will be people showing up, some from the Marvel Universe and some not. But to commit to anything more would be telling."
So yeah, I've been reluctant to assume his character would be someone from the comics. I expect we'll see a lot of original characters, though it does sound like there will be some Marvel characters too.