Lethe was a science fiction fanzine by Jack Riggs.
Lethe was published in Berkeley California, U.S.A. in the 1940s.
Issue #8 appeared in February 1948. Nine issues were published.
Along with Voice of the Imagi-Nation, Futuria Fantasia, Nova, Fantasy Fiction Telegram, Atres Artes, Le Zombie, Black Flames, Chanticleer, and Shangri L'Affaires, Lethe was included in the anthology fanzine Pacificon Combozine for the 1946 Pacificon Fourth World Science-Fiction Convention.
During the 1949s, Jack Riggs was an active fan who attended the February 1945 Boskone Convention in Boston, sponsored by The Stranger Club, and held in the home of R.D. Swisher.
With fellow fan from the 1940s Louis C. Smith, he released the fanzine Unknown Index in 1946, which was a bibliography and index to the stories and authors featured in Unknown, a pulp magazine that published science fiction, fantasy, and weird fiction.