the elder brother of Sherlock Holmes, who appears in some of the stories written by Sir Arthur Conan DOYLE . Mycroft, who is older than Sherlock, is cleverer than his younger brother but too lazy to be a detective.
the main character in the stories by Sir Arthur CONAN DOYLE . He is a very clever DETECTIVE (= someone whose job is to solve crimes and catch criminals) and he always notices very small details and then uses them to guess what has happened.