Warlock of Gramarye
1. The Warlock in Spite of Himself (1969)
2. King Kobold (1971)
2. King Kobold Revived (1984)
3. The Warlock Unlocked (1982)
4. The Warlock Enraged (1985)
5. The Warlock Wandering (1986)
6. The Warlock Is Missing (1986)
7. The Warlock Heretical (1987)
8. The Warlock's Companion (1988)
9. The Warlock Insane (1989)
10. The Warlock Rock (1990)
11. Warlock and Son (1991)
12. The Warlock's Last Ride (2004)
Odd Warlock Out (omnibus) (1989)
To the Magic Born (omnibus) (1990)
The Warlock Enlarged (omnibus) (1991)
The Warlock's Night Out (omnibus) (1991)

Rogue Wizard
1. A Wizard in Absentia (1993)
2. A Wizard in Mind (1995)
3. A Wizard in Bedlam (1979)
4. A Wizard in War (1995)
5. A Wizard in Peace (1996)
6. A Wizard in Chaos (1997)
7. A Wizard in Midgard (1998)
8. A Wizard and a Warlord (2000)
9. A Wizard in the Way (2000)
10. A Wizard in a Feud (2001)

Wizard in Rhyme
1. Her Majesty's Wizard (1986)
2. The Oathbound Wizard (1993)
3. The Witch Doctor (1994)
4. The Secular Wizard (1995)
5. My Son, the Wizard (1997)
6. The Haunted Wizard (1999)
7. The Crusading Wizard (2000)
8. The Feline Wizard (2000)

Starship Troupers
1. A Company of Stars (1991)
2. We Open on Venus (1993)
3. A Slight Detour (1994)

Crafters
1. The Crafters (1991) (with Bill Fawcett)
2. Blessings and Curses (1992)

Harold Shea (with L Sprague de Camp)
The Enchanter Reborn (1992)
The Exotic Enchanter (1995)

War and Honor (with Gordon R Dickson, David Drake and Chelsea Quinn Yarbro)
2. Blood and War (1993)

Warlock's Heirs
1. M'lady Witch (1994)
2. Quicksilver's Knight (1995)
3. The Spell-bound Scholar (1999)
4. Here Be Monsters (2001)

Star Stone
1. The Shaman (1995)
2. The Sage (1996)

Wing Commander (with William R Forstchen)
2. End Run (1993)

Mage Knight
3. Stolen Prophecy (2003)

The Gods of War (1992) (with Jody Lynn Nye, Mike Resnick)
Dragon's Eye (1994)
The Day the Magic Stopped (1995)