There are few comic book movie villains quite like Thanos. While the MCU had previously earned a reputation for somewhat lacklustre antagonists over the years, with the likes of Whiplash, Malekith, and Ronan failing to make a positive impact on the fans, the Mad Titan was different.
Marvel Studios actually allowed their big bad of the Infinity Saga a good amount of screen time and character development, teasing his first non-cameo appearance in 2018's Infinity War since way back in 2012.
The villain was made the primary focus of the third Avengers movie, was portrayed excellently by Josh Brolin, and was given a genuinely compelling and empathetic story and motivation. He didn't want to rule the world because of a mindless want for power, he truly believed what he was doing was right. In his mind, he was the hero, and he was saving the universe.
Not only did Thanos actually achieve his goal, ending Infinity War victorious, he stood by his word that he wanted nothing more than to watch over a "grateful" universe, destroying the stones that he could have used to be a god. He is one of the most memorable villains ever, but how well do you really known him?