Zelgadis is a Chimera of human, rock golem, and blue demon, transformed by Rezo, the Red Priest. Zelgadis travels the land with Lina and company to find a way to restore his humanity. Zelgadis is a very talented individual in magic, sword-fighting, and several other fields, but his forte is definitely his mastery of Shamanism. He is one of the few characters who remains rather cool and serious throughout the series, and is often the only one in the group with a level head, though he tends to get pissed off when things go awry, or when the group mistreats him (like using him as an anchor due to his weight from the rock golem).
In the series, Zelgadis says that Rezo is his great-grandfather. His great-grandfather's Rezo betrayal left him very serious, reserved, and angst-ridden. The possible effects that his transformation could have had on his psyche are unknown outside of nightmares and an increased tendency toward aggressiveness.