This article is for Sir Arthur Conan Doyle's character. For other versions of the character see Versions of Mary Watson.

Mary Watson (née Morstan) was the wife of Dr John Watson. She is first introduced in The Sign of Four and Watson refers to her in a number of the stories. While she is generally not involved in the main action of most stories, she is a central character in The Sign of Four.

Mary's father, a senior captain of an Indian regiment and later stationed near the Andaman Falls, disappeared mysteriously in 1878, a fact which would prove to be related to the mystery in The Sign of Four. Mary Morstan is Holmes' client in this story, and Watson describes her at their first meeting this way:

"She was blonde young lady, small, dainty, well gloved, and dressed in the most perfect taste. Her face had neither regularity of feature nor beauty of complexion, but her expression was sweet and amiable, and her large blue eyes were singularly spiritual and sympathetic."

Watson and Morstan fall in love during the course of the story. Watson initially hides his feelings for Morstan because she stands to inherit a fortune, and he sees it as improper and unethical to court her in view of her financial prospects relative to his own. When the treasure is lost, they both admit feelings of relief and confess their love for each other. Mary Morstan does receive a chaplet and 12 valuable pearls from Thaddeus Sholto.

She died at an unspecified point between "The Final Problem" and "The Adventure of the Empty House", and her passing is touched on briefly by Sherlock in the latter. Watson's status as a widower occasionally colours his later accounts of his friend's remarkable deeds.


Mary Morstan was portrayed by Jenny Seagrove in the feature-length episode The Sign of Four of the Granada-produced ITV series of Sherlock Holmes. Unlike her Canon counterpart, she never becomes Watson's spouse following the events of the episode, and is thus never referred to as Mary Watson.

She is a character in the Guy Ritchie films, Sherlock Holmes and its sequel, Sherlock Holmes: A Game of Shadows, where she is portrayed by actress Kelly Reilly.

In 2014, she was introduced in the BBC televised version of Sherlock in "The Empty Hearse", in which she is portrayed by Amanda Abbington, the (then) real-life partner of Martin Freeman, who plays Watson in the series. This version also married Watson in "The Sign of Three". She is eventually killed off in "The Six Thatchers" of Series 4, some months after having given birth to John Watson's baby.  

Mary Watson