As seen in: Metroid (NES)
Also in: Metroid: Other M (Wii)
Distinguishing feature: Gender-obfuscating orange battle suit of ostensible might; predilection for stripping into her latest mercenary lingerie in celebration.
Strengths: Modular power suit lends itself to adding powerful weaponry and useful gadgetry.
Weaknesses: Modular power suit lends itself to frequent, unsolicited dismantling at inopportune moments.
Let us first address the elephant in the room: Samus Aran is a woman.
Right, that wasn't very shocking, but that's only because we are the savvy gamers of the future! The video game landscape, once a world comprised almost entirely of masculine space marines, blasting aliens into smithereens in an effort to save the planet, has instead been transformed into a world comprised almost entirely of masculine space marines (some of whom are female) blasting aliens into smithereens in an effort to save the planet, thanks in no small part to heroes like Ms. Aran. Back in 1986, gamers were blasting there way through Zebes, blowing up some Mother Brain, or just Justin Bailey-ing their way to one of gaming's best shared realizations: "Hey, that Metroid dude is totally a girl!"
Ah, but wait! Here's gaming's dirty little secret: Samus wasn't the first armored alien hunter to take off her helmet at the end of the game, revealing her well-conditioned hair and soft feminine features. That honor actually belongs to Masuyo "Kissy" Toby, heroine of Namco's 1985 shooter Baraduke, which predates the first Metroid by about a year... but no one cares about that. There's a reason that the title of "First Girl Ever" in a videogame tends to be awarded to Samus.
Samus is treated with such reverence not because she's some shining example of of the power of femininity, and more because she is a sublime character in a world that is well-realized enough to do justice to her ass-kicking, planet exploring repertoire. Samus is a strong female figure that is, sadly, too rare in all forms of media, let alone video games, but let's be honest here; the fact that most of her games "reward" the player with a glimpse (however brief, modest, or pixelated it may be) of her in varying states of undress does serve to undermine the theme that she's more than just some schmuck's object of sexual desire.
Forget about all that, though. Samus is the embodiment of gameplay nirvana. She represents the pinnacle of gradual progression; each weapon she finds in the stony claws of some creepy, beaked effigy is a new way to inflict some serious hurt and, more often than not, the means to explore just a little further through whatever crazy planet she happens to find herself on. By the end of each game, Samus has become a souped up battle vixen, a whirling dervish of death and exploration and the question of whether she's actually male or female under all that orange metal becomes a seriously moot point. Then again, maybe it's best to try to finish the game in under five hours... just to see.