Dr. John H. Watson is friend and constant companion to the famous private detective Sherlock Holmes. In almost all the stories about the detective, Dr. Watson is the narrator.

When the British Empire went to fight the Second Anglo-Afghan War between 1878 and 1880 in order to secure its hegemony in the region and to prevent the attempts of the Russian Empire for expansion, Dr. Watson also did his part. During its course he suffered of a slight leg injury and has since been unable to walk normally. When his shoulder was wounded in the 1880 Battle of Maiwand, he returned to London.

While looking for a suitable apartment, he met Sherlock Holmes through a mutual acquaintance. He was looking for a roommate for his expensive apartment in London at 221b Baker Street.

Writer Sir Arthur Conan Doyle introduced Dr. Watson as a man of medium height, athletic build and about the same age as Sherlock Holmes. The detective’s female clients are often attracted by the well-educated physician. Even if Holmes and Watson have very different skills and have focused their education on distinct paths of education, their intellects are almost equal.

The detective values Watson as an intelligent interlocutor with common sense, who can come up with information in the areas in which Holmes has none or very little knowledge, such as in the field of human anatomy or political knowledge.

At the beginning of a case, Dr. Watson made the acquaintance of Mary Morstan and, after successfully solving the case, the two got married, so that Dr. Watson moved out of Holmes’ apartment. He now has his own flat together with his wife and also opened his own medical practice.

Although his time is severely limited by the marriage and the practice, Dr. Watson succeeds every now and then into assisting Holmes with his cases.

After Sherlock Holmes has seemingly been killed in his battle with Professor Moriarty at the Reichenbach Falls in Switzerland, Dr. Watson's wife, Mary, passes away, making him a widower. Therefore, Dr. Watson moves into Holmes’ apartment for a short while. Dr. Watson is said to later have remarried, but the name of his new wife remains unknown.