Out of Pod Experience

Kain: Raziel... the Abyss has been unkind.
Raziel: I am your creation, Kain. Now, as before, you criticize your own work.

"Most ironic of all, was the last gift that Raziel had given me. More powerful than the sword that now held his soul, more acute even than the vision that his sacrifice had accorded me. The first, bitter taste of that terrible illusion: hope. " - Kain

Raziel the Sarafan: "You're a righteous fiend, aren't you?"
Raziel the Reaver: "Apparently, I am."

and a long one.
Kain: Thirty years hence, I am presented with a dilemma... let's call it a two-sided coin. If the coin falls one way, I sacrifice myself and thus restore the Pillars... but as the last surviving vampire in Nosgoth, this would mean the annihilation of our species... Moebius made sure of that. If the coin lands on the reverse, I refuse the sacrifice and thus doom the Pillars to an eternity of collapse. Either way, the game is rigged.
Raziel: We agree then that the Pillars are crucial and must be restored.
Kain: Yes, Raziel, that is why we've come full-circle to this place.
Raziel: So after all this, you make my case for me. To end this stalemate, you must die so that new Guardians can be born.
Kain: The Pillars don't belong to them, Raziel... they belong to us.
Raziel: Your arrogance is boundless, Kain.
Kain: There's a third option, a monumental secret hidden in your very presence here. But it's a secret you have to discover for yourself. Unearth your destiny, Raziel. It's all laid out for you here.
Raziel: You said it yourself, Kain... there are only two sides to your coin.
Kain: Apparently so, but suppose you throw a coin enough times... suppose one day, it lands on its edge.

God, I love that series.
RIP Tony Jay (The Elder God).

Wheatley: "Alright. So that last test was... seriously disappointing. Apparently being civil isn't motivating you. So let's try things her way... fatty. Adopted fatty. Fatty fatty no-parents."
GLaDOS:"And...?"
Wheatley: "What?"
GLaDOS: "What exactly is wrong with being adopted?"
Wheatley: "Well, wha.. What's wrong with being adopted? Wha- uh... well ummm... for one lack of parents..."
GLaDOS: "(For the record you ARE adopted and that's TERRIBLE)"
Wheatley: "...and also... nothing! But.. uh.. some of my best friends are dear orphans"

“I'm Commander Shepard, and this is my favorite store on the Citadel."
-if you don't know i'm not going to tell you

also,

HK-47: "Answer: Simply that the distinction between 'killer' and 'killee' be a clear one. I cannot kill of my own volition, naturally."
Player: "I don't think 'killee' is a word."
HK-47: "Expletive: Damn it, master, I am an assassination droid... not a dictionary!"
―HK-47 KOTOR

Anything else that HK47 says (spoilers if you haven't played kotor)

Kerrigan: Captain Raynor, I've finished scouting out the area, and... you pig!
Raynor: What! I haven't even said anything to you yet.
Kerrigan: Yeah, but you were thinking it.
Raynor: Oh, yeah! you're a telepath.


Some that are drilled into my head and will never leave:

"Stay awhile and listen" -d.cain Diablo II
any unit quote from starcraft "SCV good to go!"
"Mobius One, engage" -sky eye Ace Combat 4

Embrace Eternity.

"Achtung, achtung! Panther."

Panther tanks in Company of heroes

My vision is augmented - Deus Ex
Just because I saved her doesn't mean I was going to charge up her loading ramp - Knights of the old Republic 2

There's an equipment merchant in Hellgate: London named Arlo.

"Come again soon if you're not killed by the faulty **** I sold you!"
"I stole my most crappy items from other people's toilets. I know! I have a fuckinging serious brain problem!"

"Oh I know what the ladies like" Johnson Halo 2

Pretty much everything from Portal 2

"Penetration!" World of tanks

"Dear Sarge, having fun kicking ass in outerspace, wish you were here" "I heard that, Jackass" Halo 2

"DO YOU THINK THIS IS A GAME???*Looks at camera" Jak and Daxter

Any line from the Homeworld games are gold.