Many of Farmer's works involve reworking existing characters from fiction and history, such as The Other Log of Phileas Fogg[?], filling in the missing time periods from Jules Verne's Around the World in Eighty Days, and his Riverworld series, which follows the adventures of Richard Burton and Samuel Clemens through a bizarre afterlife in which every human to ever have lived is simultaneously resurrected.
This has led to a burgeoning of a particular type of this form of fiction which is frequently referred to by reference to Farmer's original premise, the Wold Newton family.
Farmer wrote Venus on the Half-Shell under the name Kilgore Trout, a fictitious author who appears in the works of Kurt Vonnegut.
Farmer's works often contain sexual themes: his collection of short stories Strange Relations was a notable event in the history of sex in science fiction.