Now, this isn't a Forerunner, but a "Forerunner related experiment...regarding the combat suits referred to in the Waypoint data access points." It's worth mentioning this, as two things arise:
1) This is a concept piece of artwork
2) It's a Forerunner experiement
Take heed, as Forerunners have actually never been seen, with the exception of a few pieces of art showing Forerunners in various suits; we have yet to see what a Forerunner actually looks like. We've also never seen a Forerunner in a full-frontal pose with this much detail.
Also, it's badass. Here's hoping that Halo 4 brings to light more info about Forerunners, and if they actually are an alien race that advanced human evolution, or if they actually are humans.
[Via Bungie via Isaac Hanaford's personal blog]