Dallas McCord "Mack" Reynolds (November 11, 1917 – January 30, 1983) was an American science fiction writer. His pen names included Dallas Ross, Mark Mallory, Clark Collins, Dallas Rose, Guy McCord, Maxine Reynolds, Bob Belmont, and Todd Harding. His work is noteworthy for its focus on socioeconomic speculation, usually expressed in thought-provoking explorations of Utopian societies from a radical, sometime satiric, perspective. He was a considerably popular author from the 1950s to the 1970s, especially with readers of science fiction and fantasy magazines.
Reynolds was the first author to write an original novel based upon the 1966-1969 NBC television series Star Trek. The book, Mission to Horatius (1968), was aimed at young readers.