A sorcerer of Leng who possessed the body of Keiko's younger brother and tried to turn her into the avatar of the Invisible Hand. He was foiled by Motoko, Moriya and Davros, but escaped death at their hands--more precisely, they ran away once they had Keiko, and let him escape.
The Great Lo apparently died at the hands of Nausicaa, Keitaro, Kentaro and Naru during their trip to Leng; however, given his ability to steal bodies, it is not certain that the one killed was actually him.
He was known to have been a servant of the Invisible Hand, a fairly pitiful Outsider who represents market forces. The Great Lo apparently thought that Keiko's general personality made her the perfect vessel.