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.
"Yes, I'm absolutely certain it was...Gordan Freeman." --Dr. Breen, Half Life 2
"This is the Freeman. The Combine's reckoning has come." --Vortigaunt, Half Life 2
"...giving him nicknames as 'The One Free Man'..." --Dr. Breen, Half Life 2
"Crowbars are for geeky video game characters." --Anna Grimsdottir, Splinter Cell: Chaos Theory