15 books in series

Girl Genius

Girl Genius is a 15-book series with 15 released primary works first released in 2001 with contributions by Phil Foglio, Mark McNabb, Kaja Foglio, Brian Snōddy, and Cheyenne Wright.

Agatha Heterodyne and the Airship City
Agatha Heterodyne and the Monster Engine (Girl Genius, #3)
Girl Genius
Agatha Heterodyne and the Clockwork Princess (Girl Genius, #5)
Agatha Heterodyne and the Golden Trilobite (Girl Genius, #6)
Agatha Heterodyne and the Voice of the Castle (Girl Genius, #7)
Agatha Heterodyne and the Chapel of Bones (Girl Genius, #8)
Agatha Heterodyne and the Heirs of the Storm
Agatha Heterodyne and the Guardian Muse
Agatha Heterodyne and the Hammerless Bell
Agatha Heterodyne and the Siege of Mechanicsburg
Agatha Heterodyne and the Sleeping City
The City of Lightning
The Incorruptible Library
Cover 3

Sparks and Monsters

Cover 8

The Exorcism Engines