The DDT future continuity

• Saint Vidicon to the Rescue (2005)
• Escape Velocity (1983)

Starship Troupers

• A Company of Stars (1991)
• We Open on Venus (1993)
• A Slight Detour (1994)

Warlock of Gramarye

• The Warlock in Spite of Himself (1969)
• King Kobold (1971, revised as King Kobold Revived (1984))
• The Warlock Unlocked (1982)
• The Warlock Enraged (1985)
• The Warlock Wandering (1986)
• The Warlock Is Missing (1986)
• The Warlock Heretical (1987)
• The Warlock's Companion (1988)

Odd Warlock Out (omnibus) (1989)

• The Warlock Insane (1989)

To the Magic Born (omnibus) (1990)

• The Warlock Rock (1990)
• Warlock and Son (1991)

The Warlock Enlarged (omnibus) (1991)

The Warlock's Night Out (omnibus) (1991)

• The Warlock's Last Ride (2004)

Rogue Wizard

• A Wizard in Absentia (1993)
• A Wizard in Mind (1995)
• A Wizard in Bedlam (1979)
• A Wizard in War (1995)
• A Wizard in Peace (1996)
• A Wizard in Chaos (1997)
• A Wizard in Midgard (1998)
• A Wizard and a Warlord (2000)
• A Wizard in the Way (2000)
• A Wizard in a Feud (2001)

The Warlock's Heirs

• M'lady Witch (1994)
• Quicksilver's Knight (1995)
• The Spell-bound Scholar (1999)
• Here Be Monsters (2001)

A Wizard in Rhyme

• Her Majesty's Wizard (1986)
• The Oathbound Wizard (1993)
• The Witch Doctor (1994)
• The Secular Wizard (1995)
• My Son, the Wizard (1997)
• The Haunted Wizard (1999)
• The Crusading Wizard (2000)
• The Feline Wizard (2000)

Star Stone

• The Shaman (1995)
• The Sage (1996)

Crafters

• The Crafters (1991) (with Bill Fawcett)
• Blessings and Curses (1992)

Harold Shea (with L. Sprague de Camp)

• The Enchanter Reborn (1992)
• The Exotic Enchanter (1995)

Other novels

• Blood and War (1993)
• The Gods of War
• War and Honor (with Gordon R. Dickson, David Drake and Chelsea Quinn Yarbro)
• End Run (with William R. Forstchen) (1994)