From A Wiki of Ice and Fire - A Song of Ice and Fire & Game of Thrones
The Good Masters are the rulers of Astapor. Kraznys mo Nakloz is one of them.
A Storm of Swords
Daenerys contacts them under Ser Jorah Mormont's counsel in order to attempt to obtain an army of Unsullied.
- ↑ A Storm of Swords, Chapter 23, Daenerys II.