Now look at that and tell me, if the wallpaper is diablo...
The "You wil die, we promise" image.... seems to be a different Demon.
I will admit, they ressemble each other... but look carefully at the spikes coming out near the mouth...
It might be the same and its just the angle of the face but... What if we all assume we see Diablo... and its Lillith ?
and we've yet to see Diablo... he might be even scarier... o_O
Then again, the opening Cinematic, i'll admit, i kinda hope that Diablo cause he looks pretty mean ;p but... what if its Lillith hiding all this time.
What if Diablo is even scarier than that, he -is- the Lord of Terror... he should be the scariest looking of them all... he is -pure- Terror.
I'm not saying any of this is factual, i'm just theorizing, yet again ;p