Portal's Chell is quite the intelligent little devil. Navigating through GladOS's puzzles, confronting GladOS with nothing more than the Portal Gun, and destroying Aperture Labs - only to do it all again in Portal 2! If that's not enough of a resume for this gun-toting lady in heels (excuse me... Long-Fall boots) then maybe the fact that she's got the guts to leave Aperture into the open world of the Post-Half-Life series will sell you on that. Remember, she did wake up hundreds - if not thousands - of years after the first game according to this timeline.
While Chell is by far one of the more interesting characters on this list, her Portal Gun barely qualifies under our "firearm" criteria. However, her clever use of GladOS's own rocket launcher and turrets to destroy the evil computer mastermind gives her just enough destructive tendencies to earn her an honorable mention on this list.