Portal and Left4Dead have much in common, not only the names of the publishers. In both of those games the same actress is starring, Alésia Glidewell. It was her appearance that served as a prototype for the main heroine Portal, who so deftly deals with insane GLADOS. This American Beauty has also become a prototype of Zoey from the cooperative anti-zombie shooter Left4Dead.
In addition to these games from Valve, the actress also took part in creating the image of Samus for Super Smash Brothers Brawl, Neyla for Sly Cooper 2, as well as dubbed roles for Condemned Bloodshot and The Matrix: Path of Neo.