Circle of Magic (with James D Macdonald)
1. School of Wizardry (1990)
2. Tournament and Tower (1990)
3. City by the Sea (1990)
4. The Prince's Players (1990)
5. The Prisoners of Bell Castle (1990)
6. The High King's Daughter (1990)

Tom Swift (Fourth Series) (with James D Macdonald)
5. Monster Machine (1991) (as by Victor Appleton (House Name))
6. Aquatech Warriors (1991) (as by Victor Appleton (House Name))

MageWorlds (with James D Macdonald)
1. The Price of the Stars (1992)
2. Starpilot's Grave (1993)
3. By Honor Betray'd (1994)
4. The Gathering Flame (1995)
5. The Long Hunt (1996)
6. The Stars Asunder (1999)

Bad Blood (with James D Macdonald)
1. Bad Blood (1993)
3. Judgement Night (1995)

Circle of Magic 2
2. Secret of the Tower (2000)
3. The Wizard's Statue (2000)
4. Danger In The Palace (2000)
5. The Wizard's Castle (2001)

Knight's Wyrd (1992) (with James D Macdonald)
Hunter's Moon (1994) (with James D Macdonald)
Mortal Kombat (1995) by Martin Delrio ( (with James D Macdonald))
Groogleman (1996) (with James D Macdonald)
Prince Valiant (1998) by Martin Delrio ( (with Hal Foster and James D Macdonald))
A Working of Stars (2001) (with James D Macdonald)
Land of Mist and Snow (2006) (with James D Macdonald)

Robert Silverberg's Time Tours (with James D Macdonald)
3. Timecrime Inc (1991)

Daniel M Pinkwater's Melvinge of the Megaverse (with James D Macdonald and Daniel Manus Pinkwater)
2. Night of the Living Rat (1992)

Spider-Man (with James D Macdonald)
Global War (1996) (as by Martin Delrio)
Midnight Justice (1996) (as by Martin Delrio)

Earth - Final Conflict (with James D Macdonald)
Requiem for Boone (2000)

BattleTech : Mechwarrior Dark Age (with James D Macdonald)
4. A Silence in the Heavens (2003) (as by Martin Delrio)
5. Truth and Shadows (2003) (as by Martin Delrio)