Q is one of a race of omnipotent beings known as The Q. The Q encountered by the Enterprise-D is mischievous, devious, annoying, mercurial, sardonic, and a constant irritant to Captain Jean-Luc Picard each time he appears out of nowhere. He's devious and amoral and unreliable and irresponsible and....definitely not to be trusted, according to Picard.Although Q can take on any form, he usually appears as a humanoid in a Starfleet captain's uniform, mostly to thumb his nose at rank.Q mostly seems to show up to torment Picard and the crew, but his visits also occasionally have a hidden, often benevolent, purpose, or need.Background: Q is first encountered by the Federation in 2364 when he appears aboard the Enterprise-D and puts all of humanity on trial. His actions sometimes go against his own people. He has a past bad history with Guinan the bartender, which is not explained. He is fond of wearing historical costumes and zapping crew members into odd situations.