10 Comics You Must Read Before Avengers: Endgame
3. Infinity

The Mad Titan Thanos can be described as many things, one of which is that he is definitely a persistent individual. After he got taken down during the first Infinity Gauntlet ordeal, the Infinity storyline saw him make his Earth-shattering return and a galactic war ensues soon afterward.
There is a lot going on in Infinity, both on Earth and in Deep Space. The secret Inhuman city of Attilan falls and The Illuminati is forced to the frontlines, while Earth's Mightiest Heroes are prisoners of war as a result of betrayal from the Galactic Council.
This all happens after Thanos learns that his son Thane is living amongst the Inhumans on Earth. He brings his Black Order and his Outrider army to take on some very powerful heroes in what can only be described as a chaotic comeback. With Avengers: Infinity War showcasing his emotional attachment to Gamora, this story is an interesting parallel to that as well as an intriguing comparison to how he treated someone he raised in the comics versus the film.
Many of the characters heavily featured in Infinity are seen in Endgame's predecessor, so this is a good background lesson for the next Avengers film.