Thanos is known for his legacy of terror in Marvel comics and movies. But he has also lost a lot over the years. Some of his losses have been more painful than the others. Thanos is persistently brutal and continuously spreads fear and terror wherever he goes. Thanos has gained superhuman Godlike power more than once. He has also threatened the very existence of life on multiple occasions. But he has also failed a lot of times and suffered heavy losses over the years:
1. Heroes of the Earth Were Able To Stop Him: This was in Marvel comics before Civil War Captain Marvel found out that Thanos was planning to attack Earth. The precognitive, inhuman Ulysses was on her side. So Captain Marvel assembled a group of superheroes, who ultimately defeated Thanos.
2. The Cosmic Cube: Thanos is powerful, but he also needs more power to wreak destruction on the scale he usually does. So he needs power objects to help him and is forever on a quest in Marvel comics. In one such pursuit, the Heroes teamed up and defeated Thanos. They also destroyed the Cosmic Cube and killed Thanos in the process. It was his biggest failure.
3. Gamora Left Thanos: Thanos cared for Gamora, his foster daughter (as much as he could, of course). She was a brutal living weapon working for Thanos. But Gamora left him. Gamora used the skills she had learned from Thanos to escape. But the desertion hurt Thanos more than he expected it to, both in the movies and Marvel comics.
4. Thanos Couldn’t Defeat Silver Surfer Without The Infinity Gauntlet: The Silver Surfer was a powerful Cosmic being in Marvel comics who could take on Thanos and beat him. The only time he was able to defeat the Cosmic superhero was with the help of the Infinity Gauntlet.
5. He Couldn’t Defeat God Emperor Doom: During the Secret Wars (2015), Thanos was one of the survivors. God Emperor Doom knew that Thanos would overthrow him and seize his powers. So he attacked the Black Order and Thanos, thus proving his superiority.
6. Adam Warlock’s Death Would Have Benefited Thanos But He Was Never Able To Kill Him: Thanos’ Nemesis, Adam Warlock was a cosmic hero and the bane of Thanos’ existence. They fought many battles, but Thanos could never beat Adam Warlock.
7. First Captain Marvel Was Never Defeated By Thanos: Ironman was the first hero to fight Thanos, but Captain Marvel was the first to fight the mad-titan. They were arch enemies. Nevertheless, the two had some climatic encounters and grudging respect for each other’s abilities.
8. Death, his true love!: Mistress Death is one of the most feared characters in the Marvel Universe. His skepticism made him love Mistress Death because he didn’t worry her. Unfortunately, she didn’t love him – period. He never gained her love- whether or not he did what she wanted.
9. Eternals Of Titan: Thanos hated the Eternals of Titan with a vengeance. They were his people who had mistreated him as a child. They ridiculed him for years. So, his failure to destroy them is one of his most significant failures.
10. The Infinity Gauntlet: The loss of Infinity Gauntlet is Thanos’ most significant failure. Thanos was godlike and undefeatable when he had the gauntlet. Nebula grabbed it off his prone body, and he could never regain his lost glory.