The Lords of Dûs series:
- The Lure of the Basilisk (1980)
- The Seven Altars of Dûsarra (1981)
- The Sword of Bheleu (1982)
- The Book of Silence (1984)
The Worlds of Shadow series:
- Out of This World (1993)
- In the Empire of Shadow (1995)
- The Reign of the Brown Magician (1996)
The Obsidian Chronicles:
- Dragon Weather (1999)
- The Dragon Society (2001)
- Dragon Venom (2003)
The Legends of Ethshar series:
- The Misenchanted Sword (1985)
- With a Single Spell (1987)
- The Unwilling Warlord (1989)
- The Blood of a Dragon (1991)
- Taking Flight (1993)
- The Spell of the Black Dagger (1993)
- Night of Madness (2000)
- Ithanalin's Restoration (2002)
- The Spriggan Mirror (2006)
- The Vondish Ambassador (2007)
- The Final Calling (2010)
The War Surplus series:
- The Cyborg and the Sorcerers (1982)
- The Wizard and the War Machine (1987)
The Annals of the Chosen trilogy:
- The Wizard Lord (2006)
- The Ninth Talisman (2007)
- The Summer Palace (2008)
Star Trek novels:
- Voyager: Ragnarok (as Nathan Archer) (1995)
- Deep Space Nine: Valhalla (as Nathan Archer) (1995)
And one horror novel:
- The Nightmare People (1990)
Other science fiction novels:
- The Chromosomal Code (1984)
- Shining Steel (1986)
- Denner's Wreck (1988)
- Nightside City (1989)
- The Spartacus File (in collaboration with Carl Parlagreco) (2005)
- Spider-Man: Goblin Moon (as Nathan Archer, with Kurt Busiek) (1999)
- Mars Attacks: Martian Deathtrap (as Nathan Archer) (1996)
- Predator:
- Cold War (as Nathan Archer) (1997)
- Concrete Jungle (as Nathan Archer) (1995)
Other fantasy novels:
- The Rebirth of Wonder (1992)
- Split Heirs (in collaboration with Esther Friesner) (1993)
- Touched by the Gods (1997)
Short story collections:
- Crosstime Traffic (1992)
- Celestial Debris (2002)
Anthologies edited:
He has also written more than a hundred short stories including "Why I Left Harry's All-Night Hamburgers," which won the Hugo Award for Best Short Story in 1988.
Literary Criticism:-
- The Turtle Moves! (2008) - Review of the comic fantasy series by Terry Pratchett.