I've used dozens of characters from television, movies, and literature to shape the NPCs in my campaign. Rarely are they blatant copies of the character, but they serve as a springboard for their mannerisms/behaviors. A few examples:
Monaghan, an archmage and mentor to a PC in a recent campaign, was based on Archchancellor Mustrum Ridcully from Terry Prachett's Discworld. Strong, stout, stubborn, physically fit...with a outlook on life one might expect from a fighter or a ranger rather than a wizard. As a side note, the name Monaghan derives from an Irish word for an area overgrown with briars and bushes and Monaghan (the character) is known for his thick, tangled beard and hair.
Noah Roberts, grandfather of a PC in the same campaign, a legendary privateer and swordsman in his time who was still quite active despite his advanced age. He was particularly fond of telling tall tales of his travels and stories of near impossible feats...and he looked exactly like John Neville in Terry Gilliam's The Adventures of Baron Munchausen.
Wulf Hanssen, a bounty hunter/mercenary NPC, was inspired by Brock Samson from The Venture Bros. animated series. Sort of an indestrucible force of nature who preferred to kill his quarry up close and personal.