John Lucarotti (20th May 1926-20th November 1994) wrote the screenplays Marco Polo, The Aztecs, and The Massacre of St Bartholomew's Eve. He later wrote the novelisations of all three stories (see Marco Polo (novelisation), The Aztecs (novelisation) and The Massacre (novelisation).)
Lucarotti also wrote the original script for DW: The Ark in Space but was unable to do a rewrite because he was living on a boat in Corsica at the time. Robert Holmes did extensive rewrites and was credited with the story.