Agent X may refer to:

• Agent X (Music Producers), a British production and songwriting team
• Agent Extensibility Protocol, a standardised framework for extensible Simple Network Management Protocol agents
• Agent X (Chuck), the codename for the character Alexei Volkoff (Timothy Dalton) on the popular NBC TV series, Chuck
• Agent X (Marvel Comics), a fictional mercenary whose adventures have been published by Marvel Comics
• Agent X (Jim Burley), another fictional mercenary owned by Marvel Comics
• Agent X (1986 video game), a 1986 video game released by Mastertronic
  • Agent X II: The Mad Prof's Back, a 1987 sequel to this game

Agent X may also refer to:

• Secret Agent X, the title of a U.S. pulp magazine published by A. A. Wyn, and the name of the main character featured in the magazine
• Secret Agent X-9, a comic strip begun by writer Dashiell Hammett and artist Alex Raymond
  • Secret Agent X-9 (1937 serial), a 1937 Universal movie serial based on this comic strip
  • Secret Agent X-9 (1945 serial), a 1945 Universal movie serial based on this comic strip

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