I believe most of mine have been mentioned...but hell, repetition is the spice of...whatever.
Diablo I:
"WELL! WHAT CAN I DO FOR YA!?" - Griswold
"Stay a while and listen!" - Cain
"AHHH, FRESH MEAT." - The Butcher
That last one haunts me. Then again, I was a kid so... things like this [https://www.youtube.com/watch?v=t2hR6ai6q10] were kinda traumatic.
Starcraft:
Everything.
But, specifically:
"YOU MUST CONSTRUCT ADDITIONAL PYLONS!" - Adjudicator
"Nuclear launch detected!" - In each voice. I keep hearing it in my head now, thanks to an earlier poster.
"Spawn more overlords!" - Cerebrate
"For Adun!" - Zealot
"En Taro Adun! - Protoss
S.T.A.L.K.E.R. Series:
"Get out of here, S.T.A.L.K.E.R!" - Everyone and their mutated dog. In the same voice.
Warcraft III:
"Wut?" "Moar wurk!?" "Righto!" - Villager
"Shot through the heart...and I'm to blame!" - Night Elf Archer
"I said a bow string, not a G- ...nevermind." - Night Elf Archer
...Now I want to play WCIII and Starcraft. Thanks, thread.