Well known in the Half-Life universe as the first semi-intelligent companion you have, but even more so for the modification that makes her naked.

Alyx Vance is the first dynamic female character in the Half-Life series. The daughter of brilliant scientist Eli Vance, she's not only a brainiac, but she can also apparently operate any form of weaponry with ease(gee, sound familiar?). Seriously. She can kill Combine Soldiers in droves with her pistol(in Episode 1, at least), program Roller-Mines to fight for you, cover your approach to a fortified Combine position with a sniper rifle, AND she takes on ol' Freeman's reins and starts packing a shotgun, all the while making wisecracks as you go. Zombine's, anyone? Oh, and she's an expert hacker, apparently. It's almost like she's compensating for something, but it's really just Valve's excuse to throw in a badass partner. Hey, I'm not complaining.

She's not without her clearly required emotional sequences, though. She laments repeatedly through-out the first level at the fate of the ill-fortuned Combine slaves you encounter(who can shoot laser-beams at you.) Said slaves later try to lynch her on a bullet-train as you make your escape from the first level.

How did she get in contest? Episode One. Clear and simple. She walks around with you a bit, and executes some Combine for you in the first game, but not nearly to the extent of her badassery in Episode One. Still, despite her awesome revisions from the first game, it may not be enough to propel her past Lara Croft, whom in my opinion should be put out to pasture anyway. People ought to just be glad that she even got in to begin with, like with JC Denton.

Did I mention that she can also man a fixed machine gun position for you?

"Is Dr. Kleiner really telling us to...get busy?" -Alyx Vance