In his greatest and most devastating bid for power, Thanos proved one Marvel hero is the ultimate destroyer of Marvel's godlike Celestials. While many fans will know this powerhouse hero from the MCU, his comic feats are even more impressive - and yet few would guess just how jaw-droppingly powerful he proved when pitted against the creators of the Eternals and overseers of galactic life.
In the 'Thanos Wins' comic arc, the modern day Thanos is kidnapped by a version of himself from the end of time - King Thanos. This future form of the Mad Titan has slaughtered the galaxy, growing more and more powerful, finally opposed at the end of time only by a Mjolnir-wielding Silver Surfer. While King Thanos summons his younger self in the secret hope he'll finally end his long and misspent life, things don't go to his plan - a major deviation from his lifetime so far, in which he found a way to conquer every threat to his supremacy, including the Celestials themselves.
In Thanos #14 by Donny Cates and Geoffrey Shaw, Thanos reflects on his rise to power, including conquering major cosmic forces like Odin and Galactus. However, as the Mad Titan's trail of chaos threatens all life in the galaxy, the Celestials finally take action, descending on Earth to defeat him with their staggering power. However, Thanos is ready for them, and meets the Celestials with the Inhuman king Black Bolt, bound in chains. Black Bolt is one of Marvel's most powerful forces, with a whisper that can shatter mountains. As Thanos stabs the Inhuman, it turns out his scream is even enough to obliterate Celestials, as six of the gigantic beings are shattered and flung out into space.
Depicted by Anson Mount in the MCU, Black Bolt has played a pivotal role in many of Marvel's cosmic events, and his most powerful feats have challenged what fans thought was possible. For instance, in War of Kings, Black Bolt's battle with the Omega-level mutant Vulcan opened the Fault - a tear in the very fabric of Marvel's reality. However, destroying multiple Celestials with one bellow confirms that Black Bolt ranks above Hulk, Thor, and even the Sentry in terms of raw power.
It's telling that Thanos would choose not simply to destroy the Celestials using his own power, but to turn one of the galaxy's foremost protectors against it by weaponizing Black Bolt's voice - a final twist of the knife in the Mad Titan's ascent to ultimate power, when surely other avenues were available (after all, he killed All-Father Odin personally.) Black Bolt has demonstrated a mastery over his powers throughout Marvel history, but it was only in finally letting loose in 'Thanos Wins' that the Inhuman King showed that his voice truly ranks among the most destructive forces in creation - likely the reason Thanos chose to make it his weapon as part of his final victory.
Thankfully, the future of 'Thanos Wins' was overwritten after the younger Thanos decided to pursue a different kind of victory, disgusted with his future self's lack of purpose. However, Thanos is a tactical genius with an expert knowledge of the galaxy's great powers, meaning that if his final victory might eventually involve harnessing Black Bolt's voice against the Celestials, it's likely his plans against the powerful Inhuman have already been laid in Marvel's main continuity, and are just waiting to be enacted.