The directors of the series include Alice Troughton, Alex Pillai, Justin Molotnikov and Jeremy Webb. The series producer was Sara Hamill, and executive producers were Johnny Capps and Julian Murphy. It consists of 13 episodes originally shown on Saturday evenings on BBC One and BBC One HD (repeats shown on BBC Three).
The fourth series of the British drama series Merlin began on 1 October 2011 with the episode 'The Darkest Hour - Part 1'.
