Best plot twists

What are some of your favorite plot twists in games you've played? I'd like to mention a spoiler warning for anyone who hasn't played these games

Star Wars KOTOR: You ARE the villain; finding out that you really were the dark lord of the sith, and that the Jedi wiped your memories and then used you to find the Star Forge weapon is pretty jaw-dropping, hell I'd go as far as to say it rivals the "Luke, I AM your father" plot twist from Empire Strikes Back.

Bioshock: Would you kindly?; Confronting Andrew Ryan, finding out you are his son, and having to do anything he says as long as he begins it with "would you kindly", realizing you were conditioned to do anything without question as long as it began with those words, and finding out that Atlas/Fontaine had just been using you the entire game with those words, pretty amazing stuff.

Bioshock was the first game that came to mind. The last few hours of that game were mind blowing. The revealing of who Sin is in FFX was pretty surprising too (or at least it was when I was 13). Kratos's true identity caught me off guard in Tales of Symphonia too...twice.

What are some of your favorite plot twists in games you've played? I'd like to mention a spoiler warning for anyone who hasn't played these games

Star Wars KOTOR: You ARE the villain; finding out that you really were the dark lord of the sith, and that the Jedi wiped your memories and then used you to find the Star Forge weapon is pretty jaw-dropping, hell I'd go as far as to say it rivals the "Luke, I AM your father" plot twist from Empire Strikes Back.

Bioshock: Would you kindly?; Confronting Andrew Ryan, finding out you are his son, and having to do anything he says as long as he begins it with "would you kindly", realizing you were conditioned to do anything without question as long as it began with those words, and finding out that Atlas/Fontaine had just been using you the entire game with those words, pretty amazing stuff.

UT_Wrestler

.......

*SPOILER*

Shadow of the Colossus-Agro dying (or at least when you think he dies).

*SPOILER*

Bioshock-You are Andrew Ryan's genetically modified son, pretty crazy sh*t.

*SPOILER*

Mass Effect 2-The Collectors ARE the Protheans.....that's just insane. The whole building the human Reaper thing is not, however.

*END SPOILERS*

I never got the chance to play the original KotOR, but I loved the second one :D

Spoiler. Trish dying in infamous

Definitely the twist in KOTOR...

I also like the twist in Mass Effect [spoiler] Saren isn't the bad guy, his ship is...and it's a Reaper! [/spoiler]