This page compiles stories with mutants of varying abilities. I haven’t come across any short stories featuring actual Marvel X-Men. If you want this kind, you’ll probably have to stick to the comics. There are some great collection available, like:
Here are some stories with other mutants, generally written for adults and teenagers. The following stories can be found in the anthology Young Mutants.
“Hail and Farewell” by Ray Bradbury
Willie’s suitcase is packed. He knows it’s time to go. He’s been staying with Anna and Steve for three years, and people are starting to talk. He doesn’t want to go, but when people find out about his condition they get upset.
“Keep Out” by Fredric Brown
Mars is being colonized by humans. It had no intelligent life of its own, so they will become the first Martians. A group of ten-year-olds were sent to Mars. Their parents took a drug called Daptine, which would allow their children to be highly adaptable to various environments. The children will be perfectly suited to life on Mars.
“The Wonder Horse” by George Byram
Red Eagle, a horse, is from two of the best bloodlines in the breed. His parentage was arranged by Costello, a veterinarian/trainer, and Ben, a jockey. They struck a deal with their last employer in lieu of their pay. The colt’s bones are unusually long and its proportions give it powerful levers. It also has a strong heart, lungs and muscles.
“I Can’t Help Saying Goodbye” by Ann MacKenzie
Karen is nine and lives with her older brother, Max, and his wife, Libby. Her parents were killed in a bank holdup when she was seven. Before they left, she said goodbye to them slowly and clearly. After, Max remembered and said it was almost like she knew.
“Second Sight” by Alan E. Nourse
Lambertson gets back from Boston after meeting with a man named Aarons. The narrator, Amy, can tell something happened but not what. She remembers Aarons, a psychiatrist, from before she came to the Study Center. He has plans for her that Lambertson doesn’t agree with.
Read “Second Sight”
The following 3 stories can be found in the anthology The Mutant Files.
“Freak” by Charles de Lint
Bernie pleads guilty to an unstated charge. He’s been hearing voices and seeing mental pictures since he was a boy. He thought he was imagining them at first. Eventually, he realized that the voices were actually other people’s thoughts. He doesn’t invade people’s privacy on purpose; it just happens. His lawyer wanted to help, but Bernie thinks he might deserve to die.
“The Killing of Bad Bull” by Alan Dean Foster
Bull Threerivers is in a casino in Salvador, where he can blend in reasonably well. His own people want to kill him. Bull has an unusual sense for electricity—he can smell it and sense its flow. He started working in electronics repair in his teens and was masterful at it. Eventually, he realized he could use his special ability in a more lucrative way and started visiting casinos.
“Rite of Passage” by Jody Lynn Nye
A group of mutant exiles are in an obsolete freighter leaving Earth. Among the passengers are Stu, a dog-faced boy; Dimitrios, who can see lasers, infrared and other usually invisible things; and Colleen, a salamander girl; as well as others. The Anti-Mutant Act has made it impossible for mutants to earn a living. They’re being rounded up and put off Earth.
“Gray Matter” by Stephen King
The regulars are gathered at a store during a storm. Timmy Grenadine comes in looking worried. He wants Henry to bring his dad his beer because he’s too afraid to go back. Ritchie Grenadine was hurt and is on compensation. He’s gained weight and hasn’t been seen around in a while. Henry talks to Timmy a while and agrees to go check on his dad.
“Everything’s Eventual” by Stephen King
Dinky Earnshaw, a nineteen-year-old dropout, has a good job. It doesn’t pay a lot, but it comes with a house, a car, and weekly delivery of what he wants. He’s not allowed to contact any of his old friends. He’s also not allowed to save any money—whatever is left at the end of the week has to be discarded. Dinky has only met his boss, Mr. Sharpton, once. He doesn’t see who drops off his pay or the cleaners. Mr. Sharpton recruited Dinky for a special ability he possesses.
The Wild Cards Series
The Wild Cards universe is populated with Aces and Jokers—people endowed with superhuman powers and those with bizarre conditions. It’s an alternate history. After WWII, an alien virus hit the Earth, mutating those exposed to it. Some use their abilities for good, some for evil and some blur the lines.
This series is written for adults. There are some short story anthologies in this series, such as Wild Cards I: Expanded Edition, and Wild Cards II: Aces High.