M is a recurring character throughout all of the James Bond films. The character is the Head of the Secret Intelligence Service—also known as MI6—and is Bond's superior. M has appeared in the novels by Fleming and seven continuation authors, as well as appearing in twenty-four films.
In Goldeneye, M is portrayed by Judi Dench, and makes a (albeit non-physical) appearance in the 1997 video game, providing info to the player for each mission.
M will provide you with more detailed background information.
M appears on the briefing screen, providing more detail on a particular mission in compliment with background information. Though believing Bond to be a competent agent, M is often critical of his approach to various missions, such as scolding him for being jailed during the second Surface mission and his penchant for women and casinos.