Don Turnbull was a British game designer. An early contributor to White Dwarf magazine, Turnbull provided numerous monsters for their Fiend Factory column. In 1980, Turnbull was placed in charge of TSR UK Ltd., and oversaw the development of the Fiend Folio (1e) (1981). He continued to oversee numerous adventure modules during his time in charge of TSR UK, as well as the magazine Imagine.
After the decline of TSR UK, Turnbull worked for Gary Gygax at Gygax's new company, New Infinities Productions, in the U.S. However, Turnbull eventually left the gaming industry and then the U.S., returning to the UK.
Turnbull passed away in 2003.