In Ian Fleming's 007 books, he is Major Boothroyd. On screen, he has been played by Peter Burton, Desmond Llewelyn, John Cleese and Ben Whishaw.
The man who invents everything from submarine cars to collapsible helicopters, MI6's fictional quartermaster, or Q for short, has always been an integral part of the James Bond fantasy.
Except that Q is no fantasy, the head of MI6 has revealed, and he, it turns out, is a she.
Sir Alex Younger, the real-life "M", made the disclosure in a speech at the Women in IT Awards in London as part of an appeal for more women to join the Secret Intelligence Service.
Sir Alex, whose real code name is C, said: "If any of you would like to join us, the real-life Q is looking forward to meeting you and I'm pleased to report that the real-life Q is a woman."
Far from playing down the myth of invisible Aston Martins, personal jetpacks or exploding key rings, Sir Alex admitted secret gizmos had "always been there" and that the reality was beyond the realms of spy fiction.
He said: "The gadgets now that we employ - or operational technology as we more properly call it - probably defy the imagination of spy writers. So it's always been there, but technology now is at the core of what we do in a way that it wasn't before."
Sir Alex, who became head of MI6 in 2014, admitted that Bond loomed large over the service, making recruitment difficult because of the stereotype people associated with it.
He said his priority was to employ the best and that meant dispelling myths.
"The problem for me is that we've got to get over and see through the Bond thing," he said. "All right, that's good actually - let's do the Bond thing for a bit. It's great in some ways because it means that all of our opponents think there's an MI6 officer behind every bush and that we're 10,000 times larger than we actually are.
"But there's a problem because it leads to a stereotype, which is of a particular kind or a particular sort of person that will join MI6 - whether they're really posh or going to Oxford ??? I'm none of those things by the way.
"And the issue for me is that it stands in the way of something I regard as being so important, which is that we can reach into every community in Britain and make sure that we get the people that are the best regardless of their background."
Last year Mr Younger said the hard-drinking, womanising Bond would not get a job with the real MI6.
Telegraph, London