In 2267 (Stardate 2124.5), Trelane abducts crew members of the U.S.S. Enterprise to a medieval castle on the planetoid Gothos for his own amusement. He is a fan of Earth's military history, however, his knowledge of Earth is centuries out-of-date.
He is later retroactively revealed to be a member of the Q Continuum in the novel Star Trek The Next Generation: Q Squared, his relation to the Q Continuum is again visited in an issue of Star Trek Unlimited. He is considered to be a child by the standards of the Q.