One of the final "monsters" in my Rebirth FR campaign was A'tar the Merciless, a blind Dire Hyena of Legend with Divine Rank 0, in reality an ancient avatar of Amaunator (former sun god), who lived with a tribe of non-evil gnolls in the western Anauroch desert. The PCs were supposed to fight it in order to gain access to a portal in its cave, but, in the end, they managed to win the beast's favor through diplomacy and A'tar sacrificed itself to activate the portal for them to pass.
I used numerous templated monsters as uniques throughout that campaign.