Zak-Kul was a Kryptonian scientist and criminal who lived in the bottled city of Kandor. He is known for the development of an enlarging ray called Illium 349, which allowed Kandorians to grow in size and leave the city. When human Lois Lane accidentally opened the bottled city, Zak-Kul used his ray and escaped. He was later captured by Kal-El and returned to Kandor. Zak-Kul's Illium 349 was later used to enable Van-Zee to increase in size so that he could leave the city.