Fascism was a political ideology native to Earth.
The Nazis of Germany practiced a form of Fascism. (TOS episode: "The City on the Edge of Forever")
In 1954, Herbert Rossoff called Douglas Pabst a fascist after Pabst insinuated that Rossoff was a Communist. (DS9 episode: "Far Beyond the Stars")
In 2156, Nash McEvoy compared Admiral Gregory Black to a fascist. (ENT novel: Beneath the Raptor's Wing)
John Gill founded a more peaceful Fascist government on Ekos in order to stabilize the planet. (TOS episode: "Patterns of Force")
In 2364, Deanna Troi suggested that Ensign Jenny de Luz study more about Fascism in order to understand Magna Roman culture. (TNG novel: The Captains' Honor)