In the context of Marvel Comics, Lady Death refers to the personification of death as a cosmic force. Sometimes, said character is depicted as a Caucasian woman, thus resulting in the sometimes-used nicknames of either Lady Death or Mistress Death rather than the simpler and more straightforward Death. Regardless, considering the wide-reaching nature of the character, it should come as no surprise to learn that she has had a fair amount of interaction with various Marvel characters.
For example, Death has popped up in the Ghost Rider comics on at least one occasion. Furthermore, she has popped up in the stories of Ben Reilly, who is a clone of Spider-Man because comic books will be comic books. However, Death’s most famous set of interactions is with Thanos, who has shown up in the Marvel Cinematic Universe in a big way with the release of Avengers: Infinity War.
In short, Thanos’s motivation for killing such a huge percentage of the universe’s population in the comic books is based on his desire to impress Death, with whom he is more than a little bit obsessed. This was changed for the Avengers movie because Death has not been introduced to the Marvel Cinematic Universe, meaning that using that particular motivation would’ve necessitated using up a great deal of the movie’s limited time on introducing Death as well as making the users invested in Thanos’s relationship (or the lack of a relationship) with Death. Since the Avengers movie was already packed with characters, said motivation had to go, though that doesn’t actually rule out Death making an appearance in the Marvel Cinematic Universe at some point in the future.
What Might a Lady Death Movie Look Like?
With that said, Death’s role in the Marvel Cinematic Universe would be rather complicated. Simply put, she is a cosmic-level character, meaning that she possesses what might as well as be infinite power. Sure, that doesn’t stop her from getting threatened from time to time in Marvel comics because, once again, comic books will be comic books. However, a conventional threat by the standards of superhero movies seems rather inadequate, though there are ways to get around that.
For example, there is the ever-popular “protagonist loses power and must overcome challenges in spite of it” plot, which has been done before in the Marvel Cinematic Universe. However, there is also the fact that Death has planned out as well as carried out a number of plots in the Marvel comics, which could serve as inspiration for stories in which the direct use of her immense power is set aside in preference for manipulation. In fact, considering that Deadpool became infatuated with Death and vice versa at one point in the comics, it might be amusing to have her play the part of a modern day Athena in a Deadpool movie for her own reasons.
Director-wise, there is no real way to predict who should handle a story involving Death. There are too many potential stories, which in turn, mean too many potential choices. Likewise, there is no simple and straightforward choice for who should play the character because while she is sometimes depicted as a Caucasian woman, Death is the literal personification of a cosmic force, meaning that she could literally be played by multiple characters in the same movie and still make sense.