Thai Ajahns
The tradition to which both Ajahn Nitho and Ajahn Brahm belong comes from Thailand, and it was Ajahn Chah and his descendant Ajahn Liem who taught and mentored many of the Western monks.
Ajahn Ganha
Ajahn Liem
Ajahn Chah
Ajahn Ganha
Ajahn Ganha is a nephew of Ajahn Chah. Some of his teachings have been translated to English:
Location:
Wat Pah Subthawee
Nakhon Ratchasima 30370, Thailand
https://www.watpahsubthawee.org/
Map link: Wat Pah Subthawee
Ajahn Liem
Ajahn Liem was appointed by Ajahn Chah to take over and be the new leader. Some of his teachings have been translated to English:
Location:
Wat Nong Pah Pong (see below)
Ajahn Chah
Ajahn Chah was an important factor when Theravada Buddhism spread to the West, because many Westerners took an ordination with him. A lot of his teachings have been translated to English, and can be bought on Amazon. The two biggest collections of teachings in English are for free distribution:
Location:
Wat Nong Pah Pong
Ampher Warin Chamrab, Jangwat Ubon Ratchathani 34190, Thailand
http://www.watnongpahpong.org/indexe.php
Map link: Wat Nong Pah Pong
Wikipedia: https://en.wikipedia.org/wiki/Ajahn_Chah