At some unspecified moment in Portal 2, we're going to hear from Cave Johnson, the man who founded Portal research lab Aperture Science. Why we're hearing him is a mystery still unexplained.
Portal 2 takes place some time after Portal 1, but is Johnson alive? A recording that's been played back?
Cave Johnson is voiced by J.K. Simmons (Spider-Man, Oz). He is the newest character revealed for Valve's upcoming sequel. He joins a cast that includes our playable character Chell, returning antagonist GLaDOS, semi-helpful flying orb Wheatley and a pair of hero robots in the game's co-op mode. Johnson was revealed the first time at PAX East, where I recorded his debut during a theater demo.
I also recorded part of the game's excellent intro, which features Wheatley. Note that some excited PAX East attendees didn't get the memo that Portal 2 lacks voice control.