Your question is a bit too generic to answer.
As a general rule, no matter how cool he is, no one wants to hear about you character. This goes for NPC's as well as PC's.
Rather than asking for NPC's to steal, you are better off asking questions about the general process of designing interesting NPC's and adapting the ideas to your own situation.
On the generic question of, "What do I do if I want to have NPC's in my game?", the simpliest and yet probably most profound answer is, "Include them." A novel may perhaps be better served by having a small number of well realized characters. Your campaign won't be. Start off by designing in a few broad strokes scores if not hundreds of NPCs. You don't need alot of detail for any of them, just a name and a half dozen (or less) sentences about them. Don't waste time detailing them because you don't know at this point which of them will be important. What you should find happening as you run your campaign is that if you have many NPC's, some will because of the flow of events, because of quirks or accidents of the way you role-played them, because of the personality of the players, will tend to become more important. They will gain a history with the PC's and the players will become emotionally invested in them. These becoming your reoccuring NPC's.
At the outset of a campaign, you don't know what will happen. In my current campaign, a character intended in my imagination to be a major friend and ally of the party has become through a series of encounters a major foil. An NPC whom I thought the party would kill and take their stuff, is likely to become a major reoccuring villain. An NPC who I initially thought would be quiet and nerdy has turned into a jocular and well-liked friend of the party. An NPC who I thought was 'Sir Appearing Only in this Scene' is probably going to become a major quest provider. Much more is likely to happen that I didn't anticipate. The important thing is to sow in the fields of your campaign lots and lots of seeds - far more than you think you actually need - to ensure a rich harvest. NPC's will not in fact, in the long run, crowd each other out. You are going to eventually needs dozens if not scores of relations between the PC's and the NPC's, so prepare this ahead of time. If you only introduce an NPC when you think you need it for story purposes, you'll never end up with NPC's with alot of depth and more than guest appearances in single story lines. Introduce NPC's well before they are actually needed. You want to introduce the villain/mini-boss for the 5th or 6th adventure as a seemingly unimportant character when the players are as yet 1st level and have no clue really what is going on.