Final Fantasy - Obvious answer is obvious.
Civilization - how am I the only person to have included this? You all suck.

Uncharted and Mass Effect, both brilliant two-game-so-far series. I'm not sure if you can really count them due to them only being two games (so far!) but all four of those games were awesome, so... yeah.

Honourable mention to Duke Nukem. Until Duke Nukem 3D, those games were epic.