Richard Quintin Twiss (24 August 1920 – 20 May 2005) was a British astronomer. He is known for his work on the Hanbury Brown and Twiss effect with Robert Hanbury Brown. It led to the development of the Hanbury Brown-Twiss intensity interferometer in the UK in 1954. Their work appeared to contradict the established beliefs about quantum interference, and he and Brown received the Eddington Medal of the Royal Astronomical Society for it in 1968.