Outside of Wicked that Gregory Maguire mostly known for, he wrote few more title.
Below is the list of books for Adults
Wicked: The Life and Times of the Wicked Witch of the West (1995)
Confessions of an Ugly Stepsister (1999)
Lost (2001)
Mirror, Mirror (2003)
Son of a Witch (2005)
A Lion Among Men (2008)
Books for Children
The Lightning Time (1978)
The Daughter of the Moon (1980)
Lights on the Lake (1981)
The Dream Stealer (1983)
I Feel like the Morning Star (1989)
Lucas Fishbone (1990)
Missing Sisters (1994)
"The Honorary Shepherds", in Am I Blue?: Coming Out From the Silence, a collection of short stories for gay and lesbian teenagers. (1995)
Oasis (1996)
The Good Liar (1997)
"Beyond the Fringe", in A Glory of Unicorns, compiled by Bruce Coville (1998)
Crabby Cratchitt (2000)
Leaping Beauty: And Other Animal Fairy Tales (2004) with Chris L. Demarest
Hamlet Chronicles
Seven Spiders Spinning (1994)
Five Alien Elves (1998)
Six Haunted Hairdos (1999)
Four Stupid Cupids (2000)
Three Rotten Eggs (2002)
A Couple of April Fools (2004)
One Final Firecracker (2005)
What-the-Dickens: The Story of a Rogue Tooth Fairy (2007)