The Boss in MGS3 IS sexualized. Only at the end of the game, but that's enough for saying "Way to screw a fully non-sexualized female character, Kojima!".
Thank goodness she's still one of the best characters in video game history, regardless of gender.
Anthony Yates said:
Samus before other M doesn't count. Reason: She was only an avatar not a character.
Faith From mirrors edge: Same Again.
WRONG.
Samus DID have a personality in "Metroid Fusion" (the same she has in "Other M" BTW, but WAAAAY better handled) and, to a lesser but real extent, in "Super Metroid".
And Faith... well, here you're proving that you have not played the game at all.
In any case I think that people think way too much into this. It's true that sexualization can ruin some potentially good female characters (Kasumi and Ayane, I'm looking at you) and stereotypes can be a pain in the ass (Come on, "Star Ocean 4"!).
But I think that before asking ourselves if a character is sexualized or stereotipical we should ask first if the character is COMPELLING.
The reason why Alyx Vance is such a great female character is NOT because she's not stereotypical or sexualized. She is a great female character because her personality was well constructed. Nothing more, nothing less.
If a character is well constructed, then everything else is secondary. I can think of an example of this in Tifa from the original "Final Fantasy VII". She was both sexualized and stereotypical: big boobed childhood friend with a crush on the main character wearing a tank top and a mini skirt. But since her personality was well crafted those didn't matter. Her looks were a bonus, nothing more.
Too bad that was ruined in "Advent Children" and the FF VII compilation games. Even though her sexualization was severely tone down (still insanely attractive with that black outfit, though), her personality was extremely simplified and she turned into a walking stereotype. The same happened with... well... every single character in the cast.
We can find the opposite in Lightning from "Final Fantasy XIII". She's neither stereotypical nor sexualized, and still as a character she's plain terrible.