King Blackagar Boltagon, simply known as Black Bolt is a character in the 2022 film Doctor Strange in the Multiverse of Madness. He is a member of the Illuminati, who acted as their Executioner and an alternate version of Black Bolt from the mainstream timeline.
Blackagar Boltagon was the king of the Inhumans on his Earth and made protector of the Terrigen Mist who gained supersonic screams after undergoing terrigenisis. He came from a world where Tony Stark's Ultron initiative worked the way it was programmed to do. When the threats of Thanos emerged in 2018, Doctor Strange of this Earth recruited Black Bolt when he assembled the Illuminati, a group of heroes to successfully kill the Mad Titan. After Strange created an incursion in the Multiverse, Black Bolt voted to have Strange executed after he admitted to using the Darkhold to search the Multiverse for a possible solution to the conflict via dreamwalking.
Doctor Strange in The Multiverse of madness[]
After the mainstream version of Doctor Strange came to Earth-838 and stood trial, Black Bolt and the rest of his teammates, besides Mordo, were murdered by a homicidal Scarlet Witch.