Here's an obvious one, how about a Star Trek Series set in the Mirror Universe, the protagonists would be rebels fighting the Terran Empire, yes it would be in the 23rd century. I have a few ideas regarding this. How about some of the Rebels being Khan's men who rebelled against him, they managed to escape in the SS Botany Bay during the Eugenics War, that Eugenics war being fought between the victors of World War II the Americans and the Third Reich for domination of the Globe. Khan Noonan Singh throws his support in favor of the American Imperium. Defeating the Axis Powers and their race of Supermen. Some American Rebels along with some of Khans men escape on the Botany Bay. At a certain point the Botany Bay is rescued by the ISS Enterprise. This is the Mirror Universe Counterpart of the Star Trek XI movie where the Romulan Nero kills Kirk's Father and destroys Vulcan, the Mirror Universe has a different version of this story. The Rebels of the SS Botany Bay take over the ISS Enterprise and Spock joins them, and they begin plotting their revolution to overthrow the Terran Empire.
How does that sound?