Herein is presented but a single NPC - but a very detailed and well thought out one that could be dropped into a campaign at any level or, if he survives the first brush with the party, can grow with them.
Xerxes Trueflight is built around the Magus base class with the Myrmidarch archetype, with Ranger and the Arcane Archer prestige class thrown in for good measure, along with the Catfolk race... all published in various Pathfinder RPG core books. He is presented in complete detail from 1st to 20th level, usfully as indivdual stat blocks so you only need the one that's appropriate for your game - you won't have to keep flipping back and forth. Indeed, apart from levels 1 and 2, each level is on a separate page to facilitate printing only what you need.
His backstory, personality, appearance and even notes on how to role-play him are given in detail. He is very clearly intended as an opponent for your party, unlike some 'complete NPCs' he is not really suitable to be used as a player-character, at least not with the normal adventuring group. However, he isn't all bad, certainly quite three-dimensional not just someone to clobber... although the party may well have to eventually deal with him.
Nice, useful, probably an incidental (even if recurring) encounter rather than the focus of a whole campaign or even a single adventure.