Thanos is a fictional character in the Marvel Comics universe. Created by writer-artist Jim Starlin, the character first appeared in Iron Man #55 in 1973. Thanos is a supervillain who possesses superhuman strength, speed, durability, and the ability to manipulate energy. He is often portrayed as a genocidal tyrant who seeks to conquer and destroy entire civilizations, with the ultimate goal of impressing his beloved Mistress Death.

Thanos is known for his signature Infinity Gauntlet, which allows him to wield all six Infinity Stones, granting him godlike power over reality, space, time, mind, soul, and power. In the Marvel Cinematic Universe, Thanos is the main antagonist of the Infinity Saga, and his quest to collect the Infinity Stones and use them to wipe out half of all life in the universe drives the plot of several films, including Avengers: Infinity War and Avengers: Endgame.

Thanos' backstory varies depending on the source material, but he is often depicted as being born on the planet Titan, the son of Eternals A'Lars and Sui-San. As a child, Thanos was shunned by his people for his unusual appearance, and he grew up resentful of their rejection. He became obsessed with the concept of death, and began to believe that the universe was overpopulated and in need of balance. This belief led him to embark on his genocidal quest, which has made him one of the most fearsome and powerful villains in the Marvel Universe.