The Knights of Thunder, who worshiped Karana, God of Storms and Rain, were a guild of Paladins and Clerics from Qeynos who dedicated themselves to defending the Plains of Karana and other areas around Qeynos.
In a sense, they were like the druids and rangers of Surefall, in that they like to protect nature, yet they never really got themselves involved with the druids or rangers.
The Knights of Thunder also took an active role in investigating the presence of the Bloodsaber guild in the Qeynos Aquaducts.