Nick Carter-Killmaster is a series of spy adventures published from 1964 until 1990, first by Award Books, then by Ace Books, and finally by Jove Books. At least 261 novels were published. The character is an update of a pulp fiction private detective named Nick Carter, first published in 1886. The title character of the series serves as Agent N3 of AXE, a fictional spy agency for the United States government. The novels are similar to the literary James Bond novels—low on gadgets, high on action. Sexual encounters in particular are described in detail.