Hewlett, an avid science fiction fan, has been quoted saying that "Doctor Who", a sci-fi program made in his native Britain, is what first sparked his love for the genre, and that he made science fiction with his friends when he was younger in Britain, on his 8 millimetre camera. Hewlett had his early dreams of working in science fiction made into a reality, when he first had a four-episode guest role on the Canadian/American sci-fi series "Stargate SG-1", as the Stargate expert Rodney McKay, which eventually grew into his starring role on "Stargate Atlantis".