Advanced Longevity: It has been confirmed that Thanos is an extremely long-lived being and was roughly over 1000 years of age by the events of the Infinity Wars and the Battle of Earth. Even during the 2010s, he had displayed no signs of aging or any decline in his physical powers.
He's roughly over 1000 years, somewhere around 2000 or 5000. But in human years he's as old as the actor that he's played by-Josh Brolin which is 51 years old. This would make sense because Gamora is in her late teens and early adulthood and when Thanos captured her for the first time she was a child.
While it is never addressed in-universe, MCU director Joe Russo confirmed Thanos was around 1000 years old in 2012's The Avengers when he first appeared in the MCU.
Thanos is immensely strong and resistant to injury, invulnerable to nearly all types of poison, disease, and telepathic attack. He also has incredible psychic abilities; he can sense things several star systems away.
The Life of Thanos: A Tribute to the Mad Titan (MCU Explained/Recap)
How old was Thanos before Death?
However, Thanos' death occurred prior to the big time skip. Less than a full month after Infinity War, the thousand-year-old warrior destroyed the Infinity Stones to prevent them from ever being used again. He was living alone in his hut when he was confronted by an angry group of Avengers and subsequently killed.
Thanos is a mutant member of the race of superhumans known as the Titanian Eternals. The character possesses abilities common to the Eternals, but amplified to a higher degree through a combination of his mutant–Eternal heritage, bionic amplification, mysticism, and power bestowed by the abstract entity, Death.
Physically they're pretty evenly matched, but Thanos is just a much more skilled fighter. No stones were used in the fight. Per Joe Russo: "I would say that he's just that powerful," said Joe Russo.
Kulan Gath surpasses Thanos as the ultimate bad guy, as seen when he not just defeated the Avengers but killed most of Earth's heroes in a shocking and terrifying display of this Conan the Barbarian villain's power. To add insult to injury, Kulan Gath ate them afterward.
Thanos Beat Hulk Because He Was A More Skilled Fighter
Hulk's defeat could be because Thanos possessed the Power Stone, but with Thanos never pulling it out in the fight, the Russos believe that he didn't need it to win. Despite his great strength, pre-Avengers: Infinity War Hulk did not often fight with a strategy.
While Steve Rogers gets the title of the oldest human avenger, Thor Odinson, as the mighty Asgardian God of Thunder, has a much longer life span than any of his Earth-born friends.
He has feats such as defeating Surtur (who can destroy a planet), conquering the 9 realms, and sealing away Hela. While there isn't much doubt that Thanos could beat Odin if he had all 6 stones, Odin could probably defeat Thanos if he only had one or two of them.
Based on what can be deduced about his species' aging, it is possible that Groot is around 14-18 years old in The Guardians of the Galaxy Holiday Special.
While Thor is powerful and his strength is said to be unmatched, he is not strictly immortal like other mythological gods. He is susceptible both to aging and to being killed in battle. Like other Norse gods, he must consume special apples kept by the goddess Idun to keep from aging.
Thanos is an Eternal from the planet Titan who was born with a Deviant syndrome, meaning there are traces of Deviant genes within his body which gives him his hulking, purple appearance.
As Skyfather of Olympus, Zeus wields power comparable to Odin, whose wrath Thanos has withstood but not bested. At the same time, Zeus cannot truly die. While the most powerful of Olympians can be badly wounded or even dismembered, he can never actually pass on into oblivion.
As mighty as they are, neither Thanos nor Superman is immortal. Both have been killed in the past, meaning neither is unbeatable. However, Thanos would need an ironclad plan to trap and defeat the Man of Steel, because if it comes down to plain old fisticuffs, Superman is definitely going to win.
Even taking into account Thanos killing half the universe in one go, Galactus still wins on kill count. Although not every world he destroyed was inhabited or had a large population, the sheer volume of them in 13.7 billion years is unknowably vast.
Thanos would win round one. Thanos is physically superior and far more durable than Thor. In a hand to hand fight Thanos would beat Thor into a bloody pulp. I am also curious to know if Thanos can control cosmic energy outside of the gauntlet.
Thanos has another weakness: his own monstrous ego. In 1991's Infinity Gauntlet, Thanos became so powerful that he left his body to exist on another plane entirely... forgetting the Infinity Gauntlet still attached to his hand. Nebula then steals the Gauntlet for herself, undoing all of Thanos' plans.
Thanos was first introduced by Marvel in The Invincible Iron Man #55 in February, 1973. Thanos has a height of 8'3” (2.52 m) in the Marvel Cinematic Universe and 6'7” (2.01 m) in the comics.
As Death continually ignores Thanos' requests for affection, the Mad Titan loses his patience and uses the Gauntlet to create his own female companion in the form of Terraxia.
As Cates has pointed out on Twitter, it's important to point out that “Thanos” is still Thanos' real name, and that “Dione” was what his mother originally wanted to call him before he was born.
