Sixth International
The Sixth International was an organisation fighting for freedom and justice, which existed in the 1960s in an unidentified continuity before the collapse of the Multiverse. They were opposed by the Sixth Column, a cult which worshipped the fascistic deity Stardust.
The Sixth International founded the League of Liberation, a superhero team, to help them fight the Sixth Column; the group recruited, among others, Octobriana, Jenny Everywhere, Glendalf, the Magician from Mars, Butterfly, Ace Harlem, Madam Fatal and Trashman. Throughout the 1960s, their power and influence grew. In 1968, the League of Liberation finally defeated Stardust once and for all in a climactic battle, but Trashman was killed. Lacking either Stardust as a foe to rally against, or Trashman's ardent belief in the wider cause of the International as an ideal to rally behind, the team disbanded, and the Sixth International itself lost most of its power over the course of the 1970s. Subsequent efforts to reform a Seventh International were unsuccessful. (PROSE: The Hermetic Garbage of Jenny Everywhere)
Behind the scenes
The anarcho-Marxist group with access to superpowers, “the Sixth International”, debuted in the public-domain 1970s underground comics about Trashman, where “Citizen X”, a representative of the Sixth International, was the one who gave the titular character his superpowers. Interestingly, in this original context, the organisation seemed to be active in a vague dystopian near-future, instead of having its heyday in the 1960s and then disbanding.