In Avengers: Infinity War, Thanos accomplished what no villain had done before - he defeated the Avengers. This feat was largely achievable through the incredible power of the infinity gauntlet, which allowed Thanos to control space, time, and even reality itself, but does Thanos have any powers without the stones? In the movies, not really, but in the comics, absolutely.
While Thanos's backstory is not very deeply explored in the MCU, we at least know he comes from a world called Titan. This much is true in the comics as well, where it is also explained that Thanos is the son of A’lars and Sui-San, who belong to a race called the Eternals. The Eternals - who are set to have their own MCU movie in 2021 - possess a variety of powers, including super strength, invulnerability, and near-immortality. However, Thanos also carries the genes of the Deviants, the counterparts of the Eternals who have monstrous appearances. This is why Thanos looks the way he does, while the rest of the Eternals are stereotypically gorgeous.
Thanos was something of an outcast amongst the Eternals, but he shared many of their abilities. Like the Eternals, he is super-strong, resistant to injuries, immune to most poisons and diseases, and seemingly cannot die of old-age. Thanos also has a genius-level intellect, which he used to enhance his abilities even further, and is skilled in hand-to-hand combat and warfare tactics.
But The Mad Titan’s powers don’t stop there - in fact, they get even crazier. In the comics, Thanos is also capable of energy manipulation and projection (basically, he can shoot and absorb lasers) and has been shown to have both telekinetic and telepathic abilities, making him resistant to psychic attacks. Perhaps the most surprising, however, is that Thanos is also skilled in magic and the mystic arts. In Deadpool: Funeral for a Freak, Part 4, Thanos curses Deadpool with immortality so he cannot be with Death, whom Thanos has a serious crush on.
It’s not terribly surprising that most of Thanos’s abilities were scrapped for the MCU version. All those powers plus the infinity stones would have made him basically unstoppable. His super-strength alone was enough to take on Iron Man, Thor, and Captain America all at once in Avengers: Endgame. Still, with the possibility of young Thanos appearing in the upcoming Eternals movie, more of his backstory and abilities may yet be explained. Perhaps we will finally get to see what made The Mad Titan so mad in the first place.