Death is one of the Cosmic Entities in the universe.
After Loki's defeat in the Chitauri Invasion, The Other told Thanos that humanity was not as weak as they had predicted and battling them is "to court Death", to which Thanos smiled probably remembering her, with whom he shares an emotional bond.
- "Death embodies decay and can possess the soul of a living being. Often taking the form of a woman, Death can manipulate reality, time, and space, and came into existence at the same time as Entropy, Eternity, and Infinity. Immortals are immune to Death's ability. Thanos wanted to rule the universe with Death. In an attempt to impress her, he killed half of the life in the universe with the snap of his fingers."
- In an interview, Josh Brolin expanded on Thanos' relationship with Death, and confirmed that Death will be portrayed as a woman in the Marvel Cinematic Universe: "His relationship with Death, who is actually the woman, I love that. You can take Sin City (in which Brolin plays a man obsessed with a dark-hearted woman) and pump it full of steroids, and then you have Thanos. I like that he’s motivated by that — not just motivated by destruction or death or this or that. He’s motivated by a very identifiable, human trait."
- However, Death ended up being left out of Avengers: Infinity War, with Joe Russo explaining that they felt the time they would be introducing the character would be better spent focusing on just Thanos and the film's already large cast, stating "It’s our responsibility to carry forward the story as it’s been set out. You’re spending two-and-a-half hours with this many characters, so then adding in some character that the audience has no relationship to, having to explain the backstory of that character, making you care about that character, making Thanos care about that character, making that character interesting to the other characters."
- Hive, a powerful Inhuman who HYDRA reveres, was referred to as "Death" due to its fearsome nature and reputation.