Tom Corbett, Space Cadet first appeared as a television series, based on the published 1948 book "Space Cadet" by Robert Heinlein, and onscripts from an unpublished 1949 comic strip "Tom Ranger and the Space Cadets," by Joseph Greene. Greene was one of the producers of the original series, which amazingly ran on all four television networks at that early time in the medium. Actor Frankie Thomas Jr. played Tom Corbett and his likeness was used in toys and other promotional merchandise at the time. The series had wide influence and it fostered spin-off episodes in many other media including comics, books, and radio.