Star Trek: Everything We NOW Know About The Q Continuum
8. It's All About The Fans
John de Lancie is the most immediately recognisable member of the Q Continuum, for good reason. His Q, the apparently-eternal trickster, debuted in Encounter At Farpoint, thanks to some rewrites, some padding, and a little tip of the hat to a fan club president.
Janet Quarton had led the Star Trek Action Group (STAG), the group responsible for hosting the first UK Star Trek convention in 1974. She later met Gene Roddenberry, Majel Barrett, and Susan Sackett, which in turn led to several appearances at conventions. When Roddenberry received Dorothy Fontana's script for the TNG pilot, he hastily began some rewrites.
Q was added by Roddenberry, in part, to extend the pilot to feature length. Naming the character for Quarton became an ongoing gag as many of the episodes that feature the character (or the Continuum) play with the letter in the title - Hide And Q, Qpid, The Q And The Grey - ensuring the legacy of Quarton's friendship with Gene remained ever-present.