Which Sherlock character is played by Mark Gatiss in the BBC series?

Mark Gatiss plays Mycroft Holmes in the BBC series Sherlock.

Mycroft is Sherlock Holmes’s older brother and a senior figure connected to the British government. He is portrayed as exceptionally intelligent, physically inactive and often more informed about national affairs than his younger sibling.

Gatiss was not only an actor in the programme: he also co-created Sherlock with Steven Moffat and wrote several episodes. His dual role connects the production’s creative leadership with one of its most important recurring characters.

Mycroft is sometimes confused with Jim Moriarty because both are intellectual adversaries who challenge Sherlock. They are different characters: Moriarty is a criminal enemy, while Mycroft is Sherlock’s brother and an official working within the British state. Gatiss’s portrayal draws on Doyle’s Mycroft while giving him a much larger dramatic presence.