For the past four years, Marvel Studios has been setting up Thanos as the main villain of its Marvel Cinematic Universe films.

Dating all the way back to 2012’s “The Avengers,” after defeating Loki, it was shown that Earth’s mightiest heroes would have another problem on their hands when viewers watched The Other meeting with Thanos. It wasn’t until 2014 that fans would actually see Thanos, played by Josh Brolin, in “Guardians of the Galaxy.” In that film, Thanos is seen mostly in hologram form, during scenes with Ronan the Accuser and his adopted daughters, Gamora and Nebula.

While principal photography of the “Avengers: Infinity War” has yet to begin, directors Anthony and Joe Russo revealed a behind the scenes photo of actor Josh Brolin as Thanos. Dressed in a motion-capture suit, Brolin can be seen sitting as he talks with the Russo brothers. The photo’s caption simply reads, “Rehearsal.” Although much isn’t known about Thanos in the MCU, there are four things you should know about him:

1. He Will Play A Big Role In “Avengers: Infinity War”

Throughout its films, Marvel has established that items such as Red Skull’s Tesseract, Loki’s staff and Malekith’s Aether are all versions of the Infinity Gems - stones that power the Infinity Gauntlet. The Gauntlet is a glove worn by Thanos that allows the wearer to do anything he or she wants. 

2. He’s One Of Marvel’s Most Powerful

Besides characters such as the god-like One Above All and the planet-eater Galactus, Thanos is one of the Marvel Universe’s strongest characters. Thanos’ intelligence and strength means the character is rarely beaten.

3. He’s Obsessed With Death

Thanos isn’t just obsessed with the act of death, he’s obsessed with the actual Marvel character named Death. The character usually appears as a humanoid woman who possesses infinite amounts of power and knowledge. Thanos loves everything Death stands for and wants nothing more than to get her attention. While it’s uncertain if Death will appear in Marvel films, Geek.com reports that the alleged “Thor: Ragnarok” villian, Hela, may act as Death in the movie and then make her way to “Infinity War.”

4. He Doesn’t Actually Have Any Of The Infinity Gems Yet

We’ve stated already that the Infinity Gauntlet needs the Infinity Stones to operate but unfortunately for Thanos, he doesn’t have any of the stones. In the Marvel films, Thanos has failed to collect a single stone. “He’s really bad at picking henchmen,” said “Captain America: Civil War” director Joe Russo. It’s unknown what Thanos will do in the upcoming Marvel films but perhaps the villain will finally begin collecting stones. 

Josh Brolin Who is the Marvel Cinematic Universes' mysterious villain, Thanos? Pictured: Josh Brolin at the 2014 San Diego Comic Con in San Diego, California on July 26, 2014. Photo: Getty Images/Kevin Winter