Donald Tosh (16 March 1935 – 3 December 2019) was a BBC screenwriter who contributed to Doctor Who in 1965. He was the last surviving script editor and writer from the William Hartnell era. Before working on Doctor Who Tosh was briefly script editor on the series Compact, and had helped to develop the show that eventually became Coronation Street.

Tosh was the story editor for the Doctor Who stories between The Time Meddler and The Massacre of St Bartholomew's Eve, working with producers Verity Lambert and John Wiles. On Tosh's final story, The Massacre of St Bartholomew's Eve by John Lucarotti, Tosh performed a substantial rewrite of the scripts, both to align them with historical accuracy and also to accommodate William Hartnell's dual role as both the Doctor and the Abbot of Amboise. On the final episode the story editor's credit was given over to his successor Gerry Davis and Tosh was co-credited.

He also performed an extensive re-write of The Celestial Toymaker by Brian Hayles. Most of this work, however, was in turn rewritten by Davis. Tosh claimed that the trilogic game was the sole retention from his version of the script.