Two of Krakoa's main leaders, the iconic Mystique and her wife Destiny, have strongly been implied to have been Sir Arthur Conan Doyle's real-life inspiration for his Sherlock Holmes character. The strongest connection between the mutant legends and Doyle's beloved detective is the fact that Destiny's human name is Irene Adler, a name shared by a fan-favorite character from the Sherlock story "A Scandal in Bohemia."
Mystique has been a member of Krakoa's Quiet Council since the nation's formation, bringing her more than a century of experience as a warrior, spy, and detective to her role as leader of the mutants. Likewise, Destiny brings her own precognitive knowledge with her as a newly appointed leader of the Quiet Council, after she was finally resurrected by The Five during the recent Inferno event following her death more than 30 years ago at the hands of the mutant Legion.
The character of Irene Adler was first introduced as "The Woman" in 1891, and although she only appeared in one Sherlock Holmes story, her character made quite the cultural impact and she has been depicted several times in live-action franchises, like Robert Downey Jr.'s Sherlock Holmes movies as well as Benedict Cumberbatch's Sherlock TV show. Destiny first debuted in 1980s X-Men #141 as the teammate of mutant terrorist Mystique, Raven Darkhölme, but her name was not revealed to be Irene Adler until several years later. It has long been established that Raven and Irene knew each other in the early 1900s, meaning they were born in the 1800s, with Mystique never aging due to her shape-shifting ability and Destiny being incredibly old by the time of her introduction in the 1980s and subsequent death. The first hint that Irene Adler might have actually been the Irene Adler came in Claremont's first major return to the X-Men franchise, X-Treme X-Men, where Sage reveals that after Destiny wrote her famous diaries (which recently returned) that she sought out and found "consulting detective" Raven Darkhölme, the same term used to describe Sherlock Holmes role as a detective, leading to them becoming teammates and wives.
It was later confirmed that Destiny is in fact the Irene Adler from "A Scandal in Bohemia" in Chris Claremont's Chaos War: X-Men #1, where a resurrected Moira MacTaggart tells the story of Destiny and her diaries. It is revealed that Destiny's search led to her Eric Raven, a mysterious detective who looks like Sherlock Holmes and turns out to be Mystique in disguise, beginning their decades long romance and marriage. Clearly, Chris Claremont is really invested in it being canon that Destiny and Mystique were the inspiration for Sherlock Holmes, since all the major references occurred in stories her wrote, plus not only is Irene Adler the same name for both characters but Mystique's last name of Darkhölme is shockingly similar to Holmes. With Sir Arthur Conan Doyle being alive, and creating Sherlock Holmes, in the late 1800s it would not be a huge leap to think that he met Destiny and Mystique, while she was posing as the dapper Eric Raven, and was inspired by their close relationship and mysterious investigations into creating the characters of Sherlock and Irene. Fans have certainly been fond of this, as Mystique and Destiny have become popular subjects for fanart.
Mystique's shifty history as a spy mixed with meeting Destiny during the time Sherlock Holmes' creator was alive and writing stories, plus the more than similar looks and names shared between Raven and Irene and Sherlock and Irene, reveals one of the X-Men's best-kept secrets, that two of their leaders directly inspired the creation of the beloved Sherlock Holmes franchise.