When it comes to detective fiction, the more Sherlock Holmes, the better. Ever since Sir Arthur Conan Doyle created the legendary detective in 1887, Sherlock Holmes has become one of the most iconic fictional characters ever written, inspiring countless movies, television series, books, and modern reimaginations across generations including BBC’s Sherlock, Hollywood’s Sherlock Holmes films, The Adventures of Sherlock Holmes, and every interpretation has managed to captivate audiences through Holmes’ charismatic personality and the way he sees the world entirely differently from everyone else.

Yet what truly makes Sherlock Holmes unforgettable is not Holmes alone, but the world and the people surrounding him, including his best friend John Watson. Whether it is trusted allies, clever rivals, or mysterious figures operating in the shadows, these characters helped shape Holmes into the person he is, and exploring Holmes’ world through their eyes could reveal entirely new mysteries, unanswered questions, and sides of the universe fans have never fully seen before. Which is exactly why each of these 5 characters deserves a series of their own.

In any ordinary world, Scotland Yard Inspector Lestrade would probably be considered one of the finest detectives around, but this is Sherlock Holmes’ world, where deduction borders on the impossible, which often leaves Lestrade looking conventional in comparison. Unlike Holmes, he relies on standard police procedure, evidence, and lawful investigation rather than dramatic leaps of deduction, which is why Holmes often criticizes him in almost every adaptation. Yet despite all the sarcasm and frustration, Holmes deeply respects him, even calling him “the best of the professionals,” which is genuinely one of the highest compliments Sherlock Holmes could ever give someone.

If Inspector Lestrade were to get a series of his own, it could explore something Sherlock Holmes adaptations rarely focus on properly: the perspective of the man constantly trying to balance the law with a detective who barely follows it, as well as what goes on inside Lestrade’s head whenever he reaches the point of calling Sherlock Holmes for help instead of solving a case himself. There is an interesting inner struggle there, because Lestrade knows Holmes does not work like a proper officer, ignores procedure whenever he wants, and creates chaos wherever he goes, yet he also knows Holmes sees things no one else can.

BBC’s Sherlock gave audiences a glimpse of that emotional depth through Detective Inspector Greg Lestrade, showing the humanity and loyalty behind the character, but many fans still feel there is far more to explore, because Lestrade may not have Holmes’ genius, but he has patience, loyalty, discipline, and real investigative experience, which could make him easily carry a detective series of his own.

Mrs. Hudson is one of the most interesting characters in Sherlock Holmes because, in the original books, very little is actually revealed about her background. What readers do know is that she is the landlady of 221B Baker Street, the rented apartment Sherlock Holmes and Dr. John Watson always return to, which feels more like home, with Mrs. Hudson being the closest thing Holmes and Watson have to family. Despite being a supporting character, she remains one of the few constants in Holmes’ life, calmly putting up with chemical experiments, late-night violin playing, random gunshots inside the apartment, and dangerous criminals showing up at her door, all while staying fiercely loyal to both Holmes and Watson, no matter what.

What makes Mrs. Hudson especially fascinating is that while Holmes struggles to connect emotionally with most people, there is an unspoken softness and trust in the way he treats Mrs. Hudson. She has seen Holmes through exhaustion, frustration, isolation, and even moments of vulnerability that very few people ever witness, and seeing those moments from her perspective would be something fans would absolutely love. Guy Ritchie’s Sherlock Holmes films lean into the humor of her relationship with Holmes and Watson, almost like she is constantly babysitting two brilliant disasters in suits. Meanwhile, BBC’s Sherlock gives her even more emotional depth, revealing that she was once married to a drug dealer before Holmes helped free her from that life.

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The series also hints at a far more mysterious side to her, especially when she casually appears driving a red Aston Martin, leaving fans wondering how exactly Mrs. Hudson ended up with a car like that in the first place. A series of her own could finally answer those questions while showing Sherlock Holmes’ world through the eyes of the woman standing at the center of it all.

The only person intellectually superior to Sherlock Holmes is none other than his older brother, Mycroft Holmes, whom even Sherlock Holmes considers smarter than himself. Despite rarely showing his full intelligence or potential in most adaptations, Mycroft Holmes’ mysterious nature is exactly what makes him so fascinating. In the original stories, Mycroft Holmes works for the British government in an extremely influential position, indirectly revealing just how powerful and intelligent he truly is. Sherlock Holmes even describes him almost like a human information network, someone who knows secrets from every corner of the government and can connect details faster than anyone else.

However, unlike his brother, Mycroft Holmes has no interest in physical effort, danger, or chasing criminals himself. He prefers staying inside his routine, usually moving only between his home, Whitehall, and the famous Diogenes Club, which he co-founded for people who dislike social interaction, which Sherlock describes as filled with “the most unsociable and unclubbable men in town," making him one of the most interesting characters in the entire Sherlock Holmes universe.

And honestly, who does not love the brotherly banter, rivalry, hidden respect, and complicated affection between Sherlock and Mycroft Holmes? Almost every adaptation perfectly captures their constant clash of personalities, with Sherlock seeing Mycroft as lazy and too comfortable hiding behind government work, and Mycroft seeing Sherlock as reckless, emotionally impulsive, and impossible to control.

BBC’s Sherlock takes this dynamic even further by showing Mycroft’s emotional vulnerability beneath all the intelligence and control, especially when he is willing to sacrifice himself for his brother. Seeing Sherlock through Mycroft’s perspective would completely change the way fans understand both brothers, which is exactly why a series centered around Mycroft could become one of the most unique Sherlock Holmes spin-offs ever. Unlike Sherlock’s street-level detective work, Mycroft’s world moves through political conspiracies, intelligence operations, and government secrets, all of which he solves just as easily as Sherlock solves crimes. 

Irene Adler, also known as "the woman" in Sherlock Holmes’ world, is the only person who ever truly outsmarted Sherlock Holmes, becoming one of the most iconic characters in the entire universe despite appearing in only one original story by Sir Arthur Conan Doyle, A Scandal in Bohemia. What makes Irene Adler so legendary is not just her intelligence, but the fact that Sherlock Holmes, a man emotionally detached and dismissive toward almost everyone, becomes unusually fascinated by her. In the original story, despite all of Holmes’ disguises and brilliant deductions, Adler predicts his every move and escapes before he can win, leaving Sherlock genuinely shocked and caught off guard in a way very few people have ever managed.

Guy Ritchie’s Sherlock Holmes films, where Irene Adler is played by Rachel McAdams, make her far more involved in Holmes' life, transforming her into a clever thief and femme fatale with strong romantic tension between the two. The films lean heavily into their emotional chemistry while also showing Irene caught between Sherlock Holmes and Professor Moriarty.

Meanwhile, BBC’s Sherlock modernizes Irene Adler even further by portraying her as a dominatrix who weaponizes information, power, and psychological manipulation, presenting her as one of the only people capable of mentally challenging Sherlock Holmes on equal ground. Even after her limited appearances, her influence on Holmes remains long-lasting throughout the series.

However, the original story suggests something far more complex between them: admiration, respect, and intellectual fascination rather than traditional love. Holmes admires Irene because she defeats him fairly using intelligence alone, and she almost feels like the female counterpart to Sherlock Holmes himself, making Irene Adler the perfect character to lead a series of her own with psychological mind games unlike anything else in the franchise.

If Sherlock Holmes is the "consulting detective", then Professor James Moriarty is the "consulting criminal" of Sherlock Holmes’ universe. He is the closest thing the detective world has to a criminal mastermind, equivalent to Sherlock Holmes himself, making him Holmes’ greatest enemy.

In fact, Fremantle and Archery Pictures, the production company from BAFTA-nominated producer Kris Thykier, even announced a collaboration on a new original drama with the working title Moriarty, proving just how fascinating and iconic the character remains even outside Sherlock Holmes’ shadow.

What makes Moriarty especially terrifying is that he is essentially Sherlock Holmes operating on the complete opposite side of morality. Holmes describes him as a mathematical genius and former professor whose brilliance became corrupted over time. He secretly controls London’s criminal underworld while keeping his public image entirely respectable, almost like a spider sitting at the center of a giant web, pulling every string without ever getting his hands dirty.

Holmes even calls him the “Napoleon of Crime,” while Moriarty himself describes battling Sherlock Holmes as an “intellectual treat,” proving that he sees Sherlock not just as an enemy, but as the only person worthy enough to challenge him intellectually.

Despite appearing in only a few original Sherlock Holmes stories, Moriarty became one of literature’s most iconic villains because of the fear, mystery, and influence surrounding him. In Guy Ritchie’s Sherlock Holmes: A Game of Shadows, he serves as the primary antagonist secretly engineering war across Europe for profit.

However, BBC’s Sherlock completely reinvents Moriarty through Andrew Scott into someone far more chaotic, theatrical, and psychologically terrifying, almost treating crime and manipulation like entertainment itself. More than anything, this version of Moriarty sees himself reflected in Sherlock Holmes.

Even when he stands at the brink of defeating Sherlock, he finds the idea of existing without someone intellectually equal to him almost disappointing, which is exactly why his final actions become so disturbing and fascinating at the same time.

A series centered around Moriarty could honestly become one of the greatest series of the franchise ever made because it would move far beyond detective work and dive straight into manipulation, corruption, psychological warfare, criminal networks, and political conspiracies.

More importantly, it could explore what it feels like to become the only person capable of mentally standing equal to Sherlock Holmes while also becoming his complete moral opposite, two geniuses trapped on opposite sides of the same coin. So, these are the 5 major characters that definitely deserve a series of their own.

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Which of these Sherlock Holmes characters would you love to see get their own series in the future? Let us know in the comments.