Favorite flavorful NPC's

[Uhtred]

My buddy's a first-time DM looking at making his own world, and says the part that intimidates him most about the whole thing is populating his world with flavorful and interesting NPC's. I told him that he didn't have to give names and personalities and back stories and builds to every single person, just the quest-givers, the NPC's he intends to have join the party/be significant to plot, the occasional shopkeep/merchant, and of course, the bartender. Apart from that, everyone else is essentially scenery. He's a good deal less nervous knowing he needn't stat out a phone book's worth of villages.
So who are your favorite flavorful NPC's? People who have provided more than just color to the scene, who your PC's have sought out and bonded with time and again? Who you have actually given stats and back stories to?
My PC's in my Saturday campaign have grown very fond of Sebastian the Cartogromancer, a Mage whose potent magicks are bound to and spring from his enchanted maps. He's a Cleric of Farlaghn who possesses the Map of Many Lands and uses a version of the Amanuensis cantrip to copy it for his clients. Since I haven't felt like including different map merchants in every land they've visited, he has always shown up setting up a new stall just outside of town, ready to try his luck in a new town, and ready to sell his wares to the PC's, who have grown sort of attached to him, even if he thinks they're stalking him.

[Azoth]

One of my groups instanly fell in love with Tink the repair man. He was a warforged who was hold up in a podunk town out in BFE. They found him while trying to make repairs to the hull of a dilapidated and rotted out airship they were given. The party wizard was busy recharging it, as it was missing its bound elemental and its engine/battery were subsisting off of consumed arcane magic.

He was suggested by the village as he could fix most anything and had no other real use. They saw this rather logical if depressed machine lived in a shack the size of an out house, and offered him a chance to find a better life for helping them since they were flat broke and couldn't pay him.

They were impressed when he lifted the airship and held it so they could replace boards on the underside, used himself as a conductor when a harpy managed to sever the line between the battery and engine during a midair battle, and went through the abyss to bring him back when he offered up his spark of life to save them from certain doom by overloading an energy conduit in an enemy ship.

He always was just happy to travel with them, made them mechanical gifts, and in his downtime either modified himself, the ship, or crafted little figurines.

They still fly around in Tink to this day. When they freed his spark from the abyss the nearest item capable of housing it was the airship. So now he is alot like the onboard computer from Outlaw Star.

[Uhtred]

I may incorporate Warforged having Sparks, a la Transformers, into future campaigns. :) I've already got a Warforged adventuring party that combine into a Warforged Titan, like the Constructicons.