Q

Q is a member of Wammy's House exclusively in the Death Note film series continuity and in the L: Change the WorLd novel. Q is never seen in person, and they do not directly interact with the events of either the film or the novel.

Films
In the L: Change the WorLd film, Q is shown on L's mailing list along with D, P, G, I, E, and K. L emails Q and the others to inform them that Watari has died.

Novel
In the L: Change the WorLd novel, Q had designed the hacking defense security systems used in Professor Kimihiko Nikaido's research lab. Q's security system was given to Nikaido by Watari. The security system is hacked by Blue Ship when they break in to get the antidote from Nikaido.