There are 1 book by Gerard O'Callaghan on BookOrb. A strong starting point is Memories and make-believe (2013). The bibliography below is in publication order, with series grouped in reading order.
Standalone books
Frequently asked questions
How many books has Gerard O'Callaghan written?
BookOrb lists 1 book by Gerard O'Callaghan.
Where should I start with Gerard O'Callaghan?
A good starting point is Memories and make-believe (2013).
What is the Gerard O'Callaghan books in order list?
In publication order: 1. Memories and make-believe (2013).