Talos IV was a planet in the Talos star group and the homeworld of the Talosian species.
Following the visit to the planet by the USS Enterprise in 2254 the planet was quarantined by Starfleet under General Order 7. (TOS: "The Cage", "The Menagerie, Part I")
In 2387, the USS Crusader was lured to Talos IV in a plot to abduct Captain Candela Greene, and Lieutenant D'Real for experimentation, and cloning for the Zentradi. (Star Trek Crusader)