In the MCU, The Void is a place beyond time and space where things that have been "pruned" or eliminated from reality go to be destroyed into nothingness by the monstrous Alioth. It's played a major role in the Loki streaming series as well as in the recent Wolverine and Deadpool, with several characters who were trapped in the void potentially escaping.
But with the official debut of the new Thunderbolts* trailer, which seems to confirm the casting of Lewis Pullman as Bob Reynolds/The Sentry, new questions are being raised about what that could mean for The Void, because in comics, The Void is also the name of The Sentry's villainous dark side, who is powerful enough to challenge the entire Avengers and more.
