Klauth
An ancient red dragon, one of the oldest alive, living somewhere in the north — Chazlauth does not know precisely where. Unusually for a dragon of his age, he is known to have dealings with small folk.
Chazlauth named him as the likeliest "Old Wyrm of the North" referenced in the Draconic notes taken from the half-dragon at Golden Fields. That reference is the interesting part: the Cult of the Dragon's own standing orders instruct their agents that "if signs of the Old Wyrm of the North appear, withdraw." Whatever Klauth is, the Cult does not want to be near him — which makes him a potential lever against them.
Chazlauth ruled out the ancient green Old Gnawbone and the copper Vexalanthus as candidates for the title.