Ronald William "Josh" Kirby was a British commercial artist. Over a career spanning 60 years, he was the artist for the covers of many science fiction books including Terry Pratchett's Discworld novels.

Discworld is a comic fantasy book series written by the English author Terry Pratchett, set on the Discworld, a flat planet balanced on the backs of four elephants which in turn stand on the back of a giant turtle. The series began in 1983 with The Colour of Magic and continued until the final novel The Shepherd's Crown, which was published in 2015, following Pratchett's death. The books frequently parody or take inspiration from classic works, usually fantasy or science fiction, as well as mythology, folklore and fairy tales, and often use them for satirical parallels with cultural, political and scientific issues.