The Vegan Tyranny was an interstellar empire ruled by the Vegan species, which controlled a vast section of the Alpha Quadrant, centered around the planet Vega IX. They were a highly advanced civilization, with especially in the areas of cybernetics and bioengineering, having created the synthetic virus known as Vegan choriomeningitis. Having lasted for centuries, the Vegan Tyranny went extinct sometime after the 20th century. (The Worlds of the Federation)
- The Vegan Tyranny was first mentioned in James Blish's novelization of the TOS episode "Tomorrow is Yesterday", imported from his original science fiction stories.