Now here's something cosplayers would kill to have: a legitimate Corvo mask, from Dishonored. What makes it legit? Well, aside from looking totally sweet, the mask was constructed based on 3D models used by Arkane Studios during development.
The creators of this real-life mask are the talented people at special effects studio Technically Magic Effects, who actually made the mask for a competition, so it's not for sale. Arkane provided them with the source material (the aforementioned models), which means Technically Magic's creation is about as official as it gets -- at least until Bethesda licenses someone to mass produce the things.
Until then, just drool over images of this one.