There are 1 book by Wiiliam M. O'Brien on BookOrb. A strong starting point is Old Ferguson Runes (2019). The bibliography below is in publication order, with series grouped in reading order.
Standalone books
Frequently asked questions
How many books has Wiiliam M. O'Brien written?
BookOrb lists 1 book by Wiiliam M. O'Brien.
Where should I start with Wiiliam M. O'Brien?
A good starting point is Old Ferguson Runes (2019).
What is the Wiiliam M. O'Brien books in order list?
In publication order: 1. Old Ferguson Runes (2019).