Gordan Freeman

Hero that survived the Black Mesa Incident, and the Combine overtaking, of which destroyed the Citadel run by Dr. Green, former Admin of Black Mesa. MIT graduate, he worked at Black Mesa, until the incident, then was hired by the mysterious G-Man, to which he is to fulfil his every whim; next of which was the Combine overrising and destroying the Citadel. Also known as the "Free-man".

Though a destined hero, he still has no reason to speak. Curious as to how he got through school...

Gordan Freeman is the main character in the game Half like and soon in Half life 2. Was a scientist then shifted instantly to orange suited killing machine without even missing a beat.
Often seen with a crowbar

The deadliest nerd scientist on the planet. Joined Black Mesa as a scientist, put his MIT skills to the test by pushing a cart a whole 3 feet into a particle beam, caused a resonance cascade, introduced the facility to hordes of aliens, somehow survives (even though all he has is a crowbar, while the security guards with flak jackets all die), and manages to stop the cascade, only to be taken prisoner by a guy in a suit that has a funny way of talking. At least 10 years later, he is teleported back into Earth, which is now ruled by an alien race called the Combine, thanks to him. He (once again) survives against all odds, fights the Combine, goes through several plot twists, 2 sequels, and becomes a messianic figure in the eyes of Earth, all without ever speaking a word.