Dr. Julius No is a fictional character and the main antagonist in the 1958 James Bond novel and its 1962 film adaptation Dr. No, the first of the series, in which he was portrayed by Joseph Wiseman.

Dr. No is the sixth novel by the English author Ian Fleming to feature his British Secret Service agent James Bond. Fleming wrote the novel in early 1957 at his Goldeneye estate in Jamaica. It was first published in the United Kingdom by Jonathan Cape on 31 March 1958. The novel centres on Bond's investigation into the disappearance in Jamaica of two fellow MI6 operatives. He establishes that they had been investigating Doctor No, a Chinese operator of a guano mine on the fictional Caribbean island of Crab Key. Bond travels to the island and meets Honeychile Rider and later Doctor No.