A group of villains assembled by the Grandmaster inspired by Squadron Supreme as part of a contest with Kang. The alien villain Nebulon would later lead the team to try to conquer Earth. They would later be assembled again by the Grandmaster to stop Baron Zemo. An other-world counterpart of the team was the Squadron Supreme, whom where all heroes.
While not called the Squadron Sinister, the Squadron have appeared as major villains in the Disney XD series, "Avengers Assemble". However in the show, they use the name "Squadron Supreme". The roster includes Nighthawk, Hyperion, Power Princess, Speed Demon, Doctor Spectrum, and later, Nuke.