How much did Odin really know about Thanos' quest for the Marvel Cinematic Universe, the Allfather was remarkably silent about the rampaging Titan. Before the age of superheroes took off in the MCU, Odin (Anthony Hopkins) and his Asgardian kingdom were the main reason why the universe remained in peace. Thanos (Josh Brolin) then arrived during the end of his twilight days and annihilated half the universe, but the Allfather never manifested any evident sign that he knew about the forthcoming calamity.
Some events could justify the king's silence, but they're not quite convincing. After Thor (Chris Hemsworth) defeated Malekith (Christopher Eccleston) in Odin's exiled daughter Hela (Cate Blanchett) broke away from her confinement. Before dying, Odin used his last strength to make sure Thor embraced his role as the rightful king of Asgard, but Thanos proved to be more dangerous than anyone expected.
The fact that Thanos put his plan in motion as soon as Odin died suggests that the Allfather represented a considerable threat to him, but it doesn't exactly reveal how well-informed Odin was. However, it would be uncharacteristic for Odin to ignore such a powerful presence, given that he always had various tools to remain up to date with Earth and Asgard's potential enemies. Odin's ravens Huginn and Munnin always traveled across the Nine Realms to provide him with vital information, such as when Thor arrived on Earth and confronted Loki in Thanos's conspicuous movements at some point before Ragnarok arrived. Of course, none of these informants was infallible, as Thanos could have easily found a way to escape Odin's surveillance like the Dark Elves did with their cloaking devices when they slipped under Heimdall's radar and led a surprise attack on Asgard during Thor: The Dark World.
Odin was a secretive king. He managed to retain the image of a noble ruler and a peaceful kingdom after spilling blood throughout entire worlds and banishing his own daughter. It's safe to say that he wasn't eager to risk it all to maintain every possible threat under control once he accepted his waning age. What he never really let go was his infatuation with glory, as shown by the fake Infinity Gauntlet that he stored in his vault alongside his personal collection of some of the most powerful artifacts in the universe. With his renowned wisdom, the chaos that his sons' intergalactic adventures were prophesizing before his death, and the exact replica of the weapon that would cause the greatest catastrophe in the universe, he simply couldn't have overlooked the possibility of an influential figure like Thanos seizing the Infinity Stones to unleash mayhem. Knowing the very least about Thanos's previous attacks on other planets, Odin surely kept a tab on the Mad Titan.
By Avengers: Infinity War, after all) nor in a one-on-one fight. Still, he had enough magic in his body to keep him at bay. In his prime, however, it would have been a completely different story. His unassisted victories over Surtur and Hela more than speak for themselves.
Odin was one of the most powerful characters in the Marvel Cinematic Universe, but he was way past his prime when Thanos arrived. Regardless of Thanos's caution when concealing his steps, Odin always had too many helpful tools to be out of the loop. Still, his time had come and his fate was sealed, and thus a new Asgard had to endure a painful rebirth.
