This is possibly a death trope, and it may include spoilers, especially if this isn't revealed until later in the media.
Your Days Are Numbered in Comic Books.- In The Adventures of Barry Ween, Boy Genius, the titular character estimates that at the rate his Super-Intelligence is increasing he'll be driven mad by the time he's 21.
- The Batman Dailies once featured a story about a man with 10 days left to live. Oh, and he was getting married when he found out about it.
- In the one-shot Birth of the Demon, Batman takes a header into some toxic waste trying to stop people connected to Ra's al Ghul and despite Alfred asking him to go to Dr. Leslie Thompkins, he decides to use his last days hunting down Ra's, who is equally dying and is trying to create a new Lazarus Pit to revitalize himself. The story ends with both men being dragged into the pit and both being resurrected.
- In Batman: Legacy, Robin (Tim Drake) learns that the Ebola Gulf A virus wasn't cured, but went dormant and it could reawaken and kill him faster at any time. He opts to join Batman and Nightwing in trying to find a cure and stop its spread when it turns out Ra's is seeking to make a deadlier version.
- The iconic The Death of Captain Marvel deals with this as Mar-Vell learns his first fight with Nitro ended with him gaining cancer and his heroic career has caused him to mutate it into a super cancer.
- Heroic Age story 1 Month 2 Live. An ordinary man is exposed to toxic chemicals a la Daredevil. While he does gain powers, he also gains terminal cancer and the prognosis in the title. The book then becomes the story of the man and his family desperately trying to find a cure.
- Poison Ivy (2022): Ivy learns that she is dying from being fused with her Queen Ivy doppelganger and tries to do as much as she can to save the Earth from destruction before her death.
- The main plot hook of The Sculptor. 200 days.
- Shakara: Shakara is already dying because he's infected with the Red Death, the same disease that wiped out its creators and whose destruction by their enemies he is sworn to avenge. In the last issues, this becomes a Race Against the Clock as Shakara tries to stop the Big Bad from destroying all reality before he expires.
- This is the fundamental concept of Strikeforce: Morituri, where the heroes gain superpowers (to fight off an Alien Invasion) via a process that kills them inside of a year. Notably highlighted when they are reprimanded for attacking the aliens without authorization; in response, Ruth "Toxyn" Mastorakis administers a poison to her teammates, then explains it as the desperation the Morituri feel every moment they are kept away from active duty.
- Superman:
- All-Star Superman: With only a year to live due to solar radiation poisoning, Superman decides to get his last few odds and ends in order, finish off those last few bad guys, finally open up fully to Lois Lane and maybe give Lex Luthor one last thrashing.
- In The Last Days of Superman, Superman is dying from a very rare illness and has only thirty days left to live. Superman tries to get everything done before his passing, but he becomes too weakened and has to rely on Supergirl and the Legion of Super-Heroes to carry out all his remaining tasks.
- In The Final Days of Superman, Superman learns that his body is falling apart and he sets about trying to get everything in order before he passes on.
- Played with in the Infinite Frontier series. Jonathan Kent has returned from the future, and tells his father that history makes no mention of him after a certain day, when he leaves Earth. Jon is extremely reluctant to let Clark leave to help the people of War World and take up his father's mantle because of this. Clark approaches things with a Screw Destiny outlook, but does hand his son the reins of being Superman just in case Jon is correct.
- Subverted in Transmetropolitan. Spider Jerusalem learns that his mind is decaying as a result of a buildup of a certain dangerous nanotechnology in his brain — the effects are similar to Alzheimer's Disease. He is given an amount of time before he degenerates to a state of helplessness, but instead of wallowing in misery or angst, he takes a moment to feel the fear and grief, then he collects himself and tells his assistants that... well:Channon: Spider... what're you going to do? You might not be able to write a year from now. Or anything.
Spider: [magnificent bastard grin] So we've got a deadline. We can do deadlines.- And in a final subversion he turns out to be part of the one percent of victims to recover, though he keeps this a secret.
- Iron Man in The Ultimates: He became a member of the Ultimates once he found out he had an inoperable brain tumor that would eventually kill him off, and decided that he would try to do all he could to help the world if he could not help himself before he dies.
- The premise of The Wicked + The Divine. Every Ninety years, twelve gods of the Pantheon are reincarnated into the bodies of young people, all of whom will then die in two years. While none of the deaths shown so far have been natural, at one point Ananke states that the gods' "divinity would consume them soon enough". As of the 455 AD special, it appears she was correct on that score, in a gruesomely literal way!
- Once perpetrated on X-Man — essentially, there was something in his genes that would lead to his death in the near future. Warren Ellis, who wrote subsequent issues of the comic, referred to it as the "Dead At 21 TV Plot Engine" and advocated getting rid of it as fast as possible.
- Its restoration in Uncanny X-Men (2018) is a key plot point, as it's why Nate is desperate to — as he puts it — "do something good before I go", and thus became such a Well-Intentioned Extremist.
- This is part of the plot of Young Liars. In the first chapter, the reader learns that Sadie, one of the main characters, survives a gunshot wound to the head, but is told by the doctor that sooner or later, she will die due to the bullet slowly migrating through the skull.
- Youngblood (2017): Badorck, who is dying of McCall's Disease, a disease named just for him. (It's heavily implied that the experiment that gave him his powers is now killing him). This is what inspires him to help found a new Youngblood team.Badrock: I just want to be remembered for something more than "Yabba Dabba Doom". This is as close to a legacy as I'm likely to get, and I aim to make a difference before I... well, you know.
