Mokpo

Mokpo is a man living on Anodunos, who has gone totally mad, fleeing from his own bitter reality into a Dream World which he now thinks of as reality.

The Avatar met him in Ultima Underworld II inside the ice caves, but it became clear very fast that in order to flee from reality, he had become totally mad, believing reality to be a bad dream. His seemingly insane ramblings about his "real" world interested the Avatar however, so after finding the Dream Herb, the hero gave it Mokpo. When Mokpo was high on the plants, he gave interesting clues, speaking while sleeping.

Later, after traveling into the Ethereal Void, the Avatar met him again. This time, Mokpo was in his fantasy world as "Mokpo the Great," thinking himself a mighty warrior, and saying that reality was false. The Avatar left him to his delusions after getting some more hints about the nature of this world and how to beat it.

Trivia

 * The ramblings of a stoned Mokpo, combined with what he says in the Void, are in fact the complete solution for all the puzzles in that dimension.
 * Mokpo can be released from his delusions and become aware of his true surroundings.