The Titan Thanos was born on the planet Titan, and due to his severe deformities, was considered an anomaly by the Titan society and grew up as an outcast. Despite so, Thanos loved his people nonetheless.
Due to overpopulation, the planet began to run out of resources. Thanos offered a solution, to randomly kill off half of the planet's inhabitants so that the other half could truly live without having to fight each other. The Titans saw his solution to be madness and refused to let Thanos intervene. This led to Titan eventually being devastated when the people finally snapped and turned on each other for survival, and left mostly uninhabitable. The Titans themselves went nearly extinct after the conflict.
Thanos began to believe that other planets would suffer the same fate, causing him to become obsessed with “saving” the universe, by killing half of each planet's inhabitants.
Titans are much larger than humans, and their physical constitution is strong enough to wield the Infinity Stones without strain and easily overpower and severely injure beings as strong as Vision, Hulk, and Thor, as displayed by Thanos. Titans, despite their large size, possess incredible superhuman speed and reflexes that allows them to easily outmaneuver and overwhelm not only other beings of similar sizes, such as the Hulk but also even smaller and highly agile individuals as well, such as Loki, Drax the Destroyer, Gamora, and Iron Man in his Mark L Armor. They are also able to react swiftly to high-speed projectiles.
Their immortality also makes them invulnerable to most forms of damage, as even Gamora has stated that killing Thanos may not be possible, and the only known weapon with the power to kill Thanos was Stormbreaker, the most powerful weapon forged from Uru, and only if the axe was powered to the maximum and the attack was lethal. The immortal lifespan of the Titans led to overpopulation, as resources on their planet run dry, leaving only Thanos as the sole survivor of his kind.
- In the comics, the Titanians were an offshoot of the Eternals that inhabited the Saturn moon of Titan. They were mostly exterminated at the hands of Thanos.