David Geddes Hartwell was an American editor of science fiction and fantasy. He worked for Signet (1971-1973), Berkley Putnam (1973-1978), Pocket (where he founded the Timescape imprint, 1978-1983, and created the Pocket Books Star Trek publishing line), and Tor (where he spearheaded Tor's Canadian publishing initiative, and was also influential in bringing many Australian writers to the US market, 1984-date), and has published numerous anthologies. He chaired the board of directors of the World Fantasy Convention and, with Gordon Van Gelder, was the administrator of the Philip K. Dick Award. He held a Ph.D. in comparative medieval literature.

He lived in Pleasantville, New York with his wife Kathryn Cramer and their two children.