Witch World : High Halleck Cycle (with Andre Norton)
Gryphon's Eyrie (1984)
Songsmith (1992)

Starbridge
1. Starbridge (1989)
2. Silent Dances (1990) (with Kathleen O'Malley)
3. Shadow World (1991) (with Jannean Elliott)
4. Serpent's Gift (1992) (with Deborah A Marshall)
5. Silent Songs (1994) (with Kathleen O'Malley)
6. Ancestor's World (1996) (with T Jackson King)
7. Voices of Chaos (1998) (with Ru Emerson)

Exiles of Boq'urain
1. Storms of Destiny (2005)

Star Trek : The Original Series
11. Yesterday's Son (1983)
39. Time for Yesterday (1988)

V
1. V (1984)
2. East Coast Crisis (1984) (with Howard Weinstein)
9. Death Tide (1985) (with Deborah A Marshall)
V: The Original Miniseries (omnibus) (2008) (with Kenneth Johnson)

Star Trek : The Next Generation
13. The Eyes of the Beholders (1990)

Star Trek
Sarek (1994)
Sand and Stars (2004) (with Diane Duane)

Star Wars : Han Solo
1. The Paradise Snare (1997)
2. The Hutt Gambit (1996)
3. Rebel Dawn (1998)
The Han Solo Omnibus: Paradise Snare / The Hutt Gambit / Rebel Dawn (omnibus) (2000)

Aliens (with Kathleen O'Malley)
4. Resurrection (1997)