Dunn was born in Taiwan, and grew up in Taiwan, Kentucky, and San Antonio, Texas, where he graduated from Central Catholic Marianist High School. It was in Taiwan that he was first exposed to Japanese manga.
In 1984 he co-founded Antarctic Press, an American comic book company specializing in manga-style (Amerimanga) titles. His most notable creations for Antarctic are the comic book series Ninja High School and Warrior Nun Areala.