Starbase 40 was a Federation Starfleet starbase.
In the late 23rd century, the facility was expecting the arrival of the USS Enterprise but they were contacted about a delay due to the abduction of Captain Spock by the Devidians. (TOS - Convergence comic: "Split Infinities")
It had a space station facility in the 24th century. (TNG video games: Armada, Armada II)
In 2376, it was positioned in orbit of Ba'ku, where it defended the planet against a Son'a attack. (TNG video game: Armada mission: "Paradise Revisited"
- No history or fate was established for this starbase as the name was randomly assigned to a playing field station by the game software.