As common on 21st-century screens as he was in Victorian bookstores, Sherlock Holmes is one of those characters who simply refuses to die.

We mean this quite literally. In 1893, Holmes was killed off while grappling with arch-nemesis Moriarty – reportedly prompting outraged readers to don black armbands in a mixture of protest and mourning.

Though probably untrue, the story shows the regard in which Holmes was held even then, and author  Sir Arthur Conan Doyle was eventually cajoled into reviving his fallen hero.

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Doyle – who was born 160 years ago last month – himself had a colder relationship with his creation. He – correctly – felt the character cannibalised his other work (who remembers Professor Challenger?), and began to “weary of his name”. He didn’t even rate his own writing, referring to the stories as “an elementary form of fiction” (pun, one assumes, intended).

Doyle died in 1930, aged 71, but Holmes grew more vivacious with every passing decade. The Guinness Book of World Records lists him as the most portrayed character of all time – with more than 75 actors spanning more than 250 screen appearances.

Since the turn of the millennium, the centenarian Mr Holmes has been enjoying something of a purple patch. Benedict Cumberbatch rocked ratings for the BBC in Sherlock, while Robert Downey Jr  did the same on the big screen in Guy Ritchie’s soon-to-be trilogy, and Ian McKellen scored rave reviews with a more thespian take in 2015’s Mr  Holmes.

If we ignore last year’s Will Ferrell spoof, the Victorian detective has rarely been in ruder health.

How, then, has Sherlock Holmes remained so outrageously popular? Everyone loves a crime caper, and the stories were written in a modern, fast-paced, dialogue-heavy style, a far cry from the Dickensian prose that still dominated elsewhere.

First of all, what now looks like stereotype started life as innovation. Holmes existed in a pre-forensics era when most criminals were either caught in the act or not caught at all, and it’s barely a stretch to argue that his diligent clue-gathering might have influenced the development of detective work.

For instance, Holmes believed in preserving the crime scene. Now policing gospel, this detail escaped the police investigating the contemporary crime scenes of, for example, Jack the Ripper. Secondly, though Doyle was himself fascinated by The Ripper, Holmesian escapades always retained a more classical feel. In the modern age of gritty, psycho-sexual serial killer splatter, there’s something refreshing about a “missing murder weapon”, or a “corpse in a locked room”. More Cluedo than Luther, Sherlock takes the genre back to the roots he helped define.

Finally, Sherlock manages to be both instantly recognisable – he always had a strong sense of identity – while also strangely malleable.

He has endless trademarks. The pipe, the deerstalker, the plucky sidekick, the famous address, the mysterious nemesis, and the almost supernatural powers of deduction. But he is otherwise quite loosely-defined, easily bent to the whims and wishes of writer and director.

Riddled with continuity errors and contradictory characterisations, the original stories set down very few gold standards that might impede re-imaginings. “We are every bit as reverent as Doyle was to Holmes,” said BBC showrunner Steven Moffat, “which is not much at all.”

Adaptations down the years have ranged from Elementary (an ongoing American TV show with a female Watson and Moriarty), to Sherlock Hound, a canine interpretation helmed by Studio Ghibli’s Hayao Miyazaki.

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Like every good man of mystery, little is known of Holmes’ early life, so perhaps it’s better to go back to his creator. Sir Arthur Ignatius Conan Doyle was born in Edinburgh in 1859 to Irish Catholic parents. After attending Edinburgh Medical School he became a physician, published for the first time in the British Medical Journal.

Recalling the period when he was both medic and author, Doyle once said: “There was a time in my life which I divided among my patients and my literature, and it is hard to say which suffered most.”

His first novel-length manuscript was the largely autobiographical The Narrative Of John Smith. He sent his only copy to a would-be publisher, and it was promptly lost in the mail.

He’d been writing for four years by the time he contrived the character of Sherlock – first as Sheridan Hope, then as Sherrinford Holmes – famously inspired by one of Doyle’s old teachers.

Early-stage Sherlock was described as a tall, reserved 27-year-old, with sharp, piercing eyes, a dark, square-jawed handsomeness, a strong, confident handshake, and a penchant for collecting and playing rare violins. Many of these characteristics would change in future stories.

Though later Sherlock iterations would border on sex symbol status, Doyle’s Sherlock was “a reasoning and observing machine” – objective, sexless, and faintly inhuman. Irene Adler appeared in only one Doyle story, and was Holmes’ intellectual rather than physical match.

Through his glory days, Holmes served a Prime Minister of the UK, the Vatican, and the Kings of Scandinavia and Bohemia. When he met his end in The Final Problem, that was supposed to be that - but a decade later Holmes was back in action.

Perhaps ironically, it was the intervening years - known by Sherlock watchers as ‘The Great Hiatus’ - that solidified many of Sherlock’s best-known tropes. It was an 1899 stage play that popularised the detective’s deerstalker - first seen in illustrations by Sidney Paget - and his ever-present curved pipe.

Holmes initially returned with Hound Of The Baskervilles - a prequel to his fatal adventure - on a global print run of more than 100,000 copies. Like James Dean, Holmes had been immortalised by his death, but, unlike James Dean, he could come back to capitalise.

In one of the first instances of ‘retconning’, Holmes was fully revived in 1903’s The Adventure Of The Empty House, and went on to star in 32 more stories.

Today, 132 years on, the game is still afoot, and Holmes is still reaching new heights. The magnifying glass has become an iPhone; Watson’s diary has become an online blog. And “elementary, my dear Watson”, has become the rather less elegant “no s**t, Sherlock”.