My Name is Legion (Sphere science fiction) - Roger Zelazny

He'd been an important part of the team putting together the International Data Bank, which would track every single move made by every single human being. As the project neared completion, he realized that no one would ever truly be free again. At the very last moment he blanked his file, changed his face, and created a back door into the system. Now he was nameless, had no past, left no traces, according to the IDB he no longer existed. But he could become anyone at any time for any reason. Not being in the system meant that he had to earn a living outside of the normal confines of human society. But there were people willing to pay cold, hard cash for a man who could be anyone and then disappear once the job was done.