I'll start off by listing mine:
The T-800, Terminator 2: "I know now why you cry, but it's something that I can never do." Gets me every damn time.
ADA, Zone of the Enders: I think I'm the only one who played this game more than the MGS2 demo that came with it. I will never not laugh at the exchange of "You may speak like a human, but you're still a heartless computer, aren't you?" "That is correct. What is the problem?"
Codsworth, Fallout 4: He survives the nuclear holocaust despite not having a bunker and waits 200 years for you to come back. When you look at what changes his relationship with you, he mostly just wants you to be nice to people. I never swapped him out as my companion.
B.O.Y.D., Ducktales 2017: He's adorable. 'nuff said.
Legion from Mass Effect
They take the non-verbal mooks from the first game and make one of the most likable followers in the second game. His humanization of the workerbots that rose up is great and it's funny how much it pisses Tali off.
I like that the games take a pretty hardline that, yes, the slavers were indeed bad and trying to violently shut down your slave race once they gain sentience gets you exactly what you deserve, exile.
Shame that Mass Effect 3 has the "best" ending for the Geth be the one where they make peace with the Quarians (who are actively trying to genocide them again) and then quietly leave their homeworld after helping the Quarians recolonise it.
I thought they lived together on the planet? It seemed like the Geth weren't too pissed about the whole thing. More confused. The Quarians on the other hand took it very personally.
In 2 and 3 at varying points, Quarians bring up that they've already separated out where they're going to live after they've destroyed the Geth. It's unclear what happens if the Geth already have a presence there. And there's dialogue after Rannoch is completed about them making space for the Quarians.
According to the in-game encyclopedia there's very little fertile ground on Rannoch, so the servers you see during Priority: Rannoch are probably not staying where they are.
In retrospect, I'm probably wrong about them being moved offworld, but the Geth are definitely being shunted into the uninhabitable wasteland.
Oh yeah, the Quarians have genocidal intentions. I just kind of remember them getting over it in the "best ending". I'm not sure I ever did that though. I either sided with the Geth or Quarians and wiped one or the other out.
Whether or not the Quarians or the Geth wipe the other out is largely decided on if you choose to save, like, a single fleet admiral.