Richard L. Tierney (born 1936) is an American writer and poet. Tierney, a scholar of H. P. Lovecraft, has written Cthulhu Mythos novels and is the coauthor (with David C. Smith) of a series of Red Sonja novels, featuring cover art by Boris Vallejo.
Tierney was one of the first to challenge August Derleth's interpretation of Lovecraft's creations in his notable article "The Derleth Mythos", published in Meade and Penny Frierson's fanzine H.P.L. (1973). In an interview for Sword & Sorcery magazine Tierney said, however that he considers his own mythos work to be in the Derlethian vein:
"I don't feel my writing has taken up "the line of Lovecraft's development." Rather, I appear to have taken up and developed Derleth's vision of the Mythos". 
- The Winds of Zarr (Silver Scarab Press, 1975) featuring John Taggart.
- For The Witch Of The Mists (Ace Books, 1978), with David C. Smith, featuring Bran Mak Morn.
- The House of the Toad (Fedogan and Bremer, 1993)
- The Gardens of Lucullus (Sidecar Preservation Society, 2001), (with Glenn Rahman), featuring Simon Magus.
- The Drums of Chaos (Mythos Books LLC, Sept. 2008), featuring Simon Magus and John Taggart.
- The Ring of Ikribu (Ace 1981) (Adapted to comics by Roy Thomas and Esteban Maroto in The Savage Sword of Conan issues 230-3)
- Demon Night (Ace 1982)
- When Hell Laughs (Ace 1982)
- Endithor's Daughter (Ace 1982)
- Against the Prince of Hell (Ace 1983)
- Star of Doom (Ace 1983)
- Tigers Of The Sea (1975), with Robert E. Howard (posthumous collaboration), featuring Cormac Mac Art.
Simon Magus series:
- Scroll of Thoth: Simon Magus and the Great Old Ones (Chaosium, 1997) collects all 12 Simon Magus stories solely written by Richard L. Tierney. A partial list of original publication locations and dates is on-line at the Crypt of Cthulhu archive. 
Not included in this collection are:
- The Wedding of Sheila-Na-Gog (Crypt Of Cthulhu #29, 1985), with Glenn Rahman.
John Taggart series:
- Countdown for Kalara (Space and Time, Jul 1980)
- The Last Decision (Eldritch Tales #15 1988)
- Collected Poems: Nightmares and Visions (Arkham House 1981)
- The Blob That Gobbled Abdul And Other Poems And Songs (Sidecar Preservation Society)