Andrew Paul Marshall (born 27 August 1954) is a British comedy screenwriter, most noted for the domestic sitcom 2point4 children. He was also the inspiration for Marvin the Paranoid Android in The Hitchhiker's Guide to the Galaxy. Although he had also previously adapted stories for Agatha Christie's Poirot, in 2002 he made a further move into writing "straight" drama, with the fantasy horror series Strange. He has also written several screenplays.

Born in Lowestoft, Marshall attended Fen Park School and then Lowestoft Grammar School, and afterwards Borough Road College where he studied mathematics and psychology. Around the same time, he worked regularly on Radio 4's Week Ending, together with David Renwick, Douglas Adams, Alistair Beaton, John Lloyd, Simon Brett and others. Shortly afterwards he began writing The Burkiss Way with David Renwick and John Mason (who later dropped out to go to acting school). Renwick and Marshall remained scriptwriting partners for many years.