Fonstad's speciality was the creation of fictional atlases:
- The Atlas of Pern (1984, ISBN 0-345-31434-4)
- Pern, based on the Dragon Riders stories by Anne McCaffrey
- The Atlas of the Land (1985, ISBN 0-345-31431-X)
- The Land, based on The Chronicles of Thomas Covenant by Stephen R. Donaldson
- Atlas of the Dragonlance World (1987, ISBN 0-88038-448-4)
- Krynn, based on the DragonLance stories by Tracy Hickman and Margaret Weis (among others)
- The Forgotten Realms Atlas (1990, ISBN 0-88038-857-9)
- Forgotten Realms, published by TSR
- The Atlas of Middle-earth (2001, ISBN 0-618-12699-6)
- Middle-earth, based on The Lord of the Rings by J. R. R. Tolkien