The Ancient One wouldn't have been able to go toe-to-toe against Odin in his prime. She even failed to beat her former student and dark dimension rookie Kaecilius (Mads Mikkelsen) in physical combat.
While Odin was strong during his prime, Thor was just naturally stronger than him. They don't call Thor the mightiest out of all of the Asgardians for nothing because he is actually a lot stronger than his father in terms of his physical capabilities.
Addendum: Though Thanos indeed beat the Ancient One's successor in a one on one fight during Infinity War, Thanos was also already in possession of 4 Infinity Stones when that battle took place.
He is capable of astral projection, thought projection, and mental possession with a range of power encompassing the entire Earth. He can project and manipulate numerous forms of mystic energy to transform, animate, levitate, or otherwise alter physical objects.
Surtur, the fire demon, forges a sword called Twilight which would bring about the end of Asgard and Earth. Odin perishes many times facing him and ultimately gets caught in eternal combat with the demon.
That is exactly what the goddess Hel was. Being the daughter of Loki already made her very powerful. However, in her realm of the underworld, this half-decaying goddess was said to be even more powerful than Odin and many other Norse gods.
Thanos was scared of the ancient one, Odin, and Ego. That's why Thanos didn't show up until infinity war.
Clearly, the Ancient One is more experienced and superior with her skills; Hela wouldn't stand a chance against her. And since, we don't think Hela can travel across dimensions on her own, she would be trapped.
The results indicated an age older than 9,000 years, making The Ancient One among the oldest and most complete skeletons found in North America. Subsequent research on the bones indicated that the skeleton is between 8,400–8,690 years old.
The Ancient one would win in all the Marvel universes given any plausible plot. In the MCU movie, 'Avengers Endgame', the Ancient one basically incapacitates Thor in less five minutes.
Based on the analysis of powers, speed, strength, durability, and combat, we can safely say that Odin is stronger than Thanos and outmatches him in almost every aspect. Thanos might be among the most feared villains in the Marvel Universe, but he comes nowhere near when compared to All-Father Odin.
Ancient One warping space The Ancient One's connection to the Dark Dimension allowed her to warp space in the Mirror Dimension. Her momentum was enhanced to the point that she can easily send someone flying with her strikes.
History. One Above All was one of the many victims of Thanos in his eternal quest to please Death. He was obliterated along his fellow Celestials by Thanos when he stabbed Black Bolt to death in order to use his destructive voice as weapon.
Galactus would win in a fight against Odin. Odin and Galactus are practically equal in their respective power levels, but they are stronger, more durable, and faster. Odin's only chance at defeating Galactus is if the latter is starved or poorly fed.
The trivial answer is that Odin cannot lose to Zeus because Zeus is not Fenrir and, according to Norse mythology, Odin has been prophesied to be swallowed by Fenrir in Ragnarok. Odin cannot die before then so Zeus cannot win.
The Odin Fight In AC Valhalla Explained
Odin cannot be beaten traditionally and requires more than a sharp weapon to defeat. Near the end of the game, players will confront Odin in a sort of dreamscape. Odin is armed with his spear and will taunt players while he attacks them.
Marvel Cinematic Universe
Tilda Swinton as the Ancient One in Doctor Strange (2016).
The film starred Tilda Swinton as the Ancient One, Doctor Strange's mentor and a Celtic mystic who resided in Kamar-Taj, a location in the Himalayas. In the comics, Ancient One is a Tibetan man, and thus the film's production and release were surrounded by accusations of whitewashing.
Hela is the Asgardian God of Death and the daughter of Loki. She has access to the power of life and death as well as ancient and deadly magics. Thor himself has never defeated Hela, and Aquaman would certainly find himself unable to defeat Hela.
Unable to kill his own daughter, Odin defeated Hela and imprisoned her using his own power to keep her at bay in another realm for eons. During this respite, Hela attempted to escape imprisonment in Hel and was near successful.
So, coming back to the question, Loki is no match for the Ancient One.
Loki – Thor's archenemy and adoptive brother.
Instead of aliens, androids, and wizards, Thanos is afraid of aliens, Asgardians, and wizards. The theory posits Ego, Odin, and The Ancient One as three of Thanos' greatest fears, and he waited until all of them were dead to make his move.
As per the user, the director of Avengers confirmed that Thanos was most scared of Iron Man. “Not because of his strength, not because of his power, not because of his power, but because of his suit,” he added.