Thief, Thief Gold, and Thief II... three of the best games ever made.
Well, two actually. Thief Gold is Thief, but with a few levels enhanced and added (including a blooper level)

EDIT: Thief II had some great levels (LOVE Crashing the Party, where not only do you explore the city from the rooftops, you also explore a huge tower), but Sabotage at Soulforge made feel like I was not controlling Garrett, Master Thief, but rather Garrett, Factory Worker. *sigh*