Pelor was a deity with the domains of healing and the sun. He was slain by Tiamat in the first recorded use of the Death Equation. Shortly there after, when Delvash slew Tiamat and absorbed her domains, he didn't have enough power to contain the domain of the sun. He had to release the power of the sun back into the sky, where the spirit Raos now acts as protector of the sun.
When he was still alive, he befriended Balvan the Millstone, and was in fact responsible for teaching him how to manifest a humanoid avatar. The temple Balvan built to Pelor is still present in the bowels of Mount Pillar, and now serves as home to the Mount Pillar Lich.