GLaDoS.
Except the missile launcher would fire trollfaces at you. And if you don't beat her by the time the timer runs out, LulzSec hacks you. And all the cores are wearing the Anynonymous masks. And every 10 seconds, the fight takes place in a different game. However, you need not undertake this fight alone. Standing with you are all the paradigms that make up the good of the internet: The Escapist, MMO players who aren't Douchebags (and trust me from experience, the ones who aren't Doucebags are quite good people), Al Gore, The Reds and the Blues, the Cake, and most importantly... the Companion Cube.
Not to mention your Portal Gun is replaced with the Sword of Moderation.
So, yeah, essentialy it's Internet Good, vs Internet Evil. And GLaDoS is only in there because she controlls the darn thing anyway, so you'd have to take it from her to "win" the internets