John H. Watson, M.D., known as Dr. Watson, is a character in the Sherlock Holmes stories by Sir Arthur Conan Doyle. Watson is Sherlock Holmes's friend, assistant and sometime flatmate, and is the first person narrator of all but four stories in the Sherlock Holmes canon.
Doctor Watson's first name is mentioned on only three occasions. Part one of the very first Sherlock Holmes story, A Study in Scarlet, is subtitled 'Being a reprint from the Reminiscences of John H. Watson, M.D., Late of the Army Medical Department'. In '"The Problem of Thor Bridge"', Watson says that his dispatch box is labeled 'John H. Watson, M.D'. Watson's wife calls him 'James' in "The Man with the Twisted Lip"; Dorothy L. Sayers speculates that Morstan may be referring to his middle name Hamish (which means James in Scottish Gaelic), though Doyle himself never addresses this beyond including the initial. In every other instance, he is called either Doctor or Watson, or both together, and his first name is never used again.
In A Study in Scarlet, Watson, as the narrator, recounts his earlier life before meeting Holmes. It is established that Watson received his medical degree from the University of London in 1878, and had subsequently gone on to train at Netley as a surgeon in the British Army. He joined British forces in India, saw service in the Second Anglo-Afghan War, was wounded at the Battle of Maiwand, suffered enteric fever and was sent back to England on the troopship HMS Orontes following his recovery.
In 1881, Watson runs into an old friend of his named Stamford, who tells him that an acquaintance of his, Sherlock Holmes, is looking for someone to split the rent at a flat in 221B Baker Street. Watson meets Holmes for the first time at a local hospital, where Holmes is conducting a scientific experiment. Holmes and Watson list their faults to each other to determine whether they can live together, concluding that they are compatible; they subsequently move into the flat. When Watson notices the multiple guests which frequently visit the flat, Holmes reveals that he is a "consulting detective" and that the guests are his clients.
By this time, Watson has already become impressed with Holmes' knowledge of chemistry and sensational literature. He witnesses Holmes' amazing skills at deduction as they embark on their first case together, concerning a series of murders related to Mormon intrigue. When the case is solved, Watson is angered that Holmes is not given any credit for it by the press. When Holmes refuses to record and publish his account of the adventure, Watson endeavours to do so himself. In time, Holmes and Watson become close friends.
In The Sign of the Four, John Watson becomes engaged to Mary Morstan, a governess. In "The Adventure of the Empty House", statements by Watson imply that Morstan has died by the time Holmes returns after faking his death; that fact is confirmed when Watson moves back to Baker Street to share lodgings with Holmes, as he had done as a bachelor. Conan Doyle made mention of a second wife in "The Adventure of the Illustrious Client" and "The Adventure of the Blanched Soldier", but this wife was never named, described, or explained.
When John Watson first returns from Afghanistan, he is described "as thin as a lath and as brown as a nut." He is usually described as strongly built, of a stature either average or slightly above average, with a thick, strong neck and a small moustache. Watson used to be an athlete, as it is mentioned in "The Adventure of the Sussex Vampire" that he once played rugby for Blackheath, but he fears his physical condition has declined since that point.
Although "Elementary, my dear Watson" is perhaps Holmes's best-known catch phrase, he never uses exactly those words in any of the books written by A. Conan Doyle.