The planet falsely disclosed to Darth Vader by Princess Leia as the location of the secret base of the Rebel Alliance in Star Wars Episode IV: A New Hope. Leia attempted to avoid the destruction of her home planet of Alderon and withold the location of the base, only to still have her planet decimated by the Death Star.
"You wish to save your planet from destruction? Then, name the system..."
"Dantooine. The base is on Dantooine."