Acquiring eyes consists in a major evolutionary transition since it requires the assembly of several functionally integrated components, and strongly impacts the lifestyle of an organism. While eyes evolved many times in bilaterian animals with elaborate nervous systems, image-forming and simpler eyes also exist in cnidarians, which are ancient non-bilaterians with neural nets and regions with condensed neurons to process information. How often eyes of varying complexity, including image-forming eyes, arose in animals with such simple neural circuitry remained obscure. With large-scale phylogenies of Cnidaria and their photosensitive proteins, we show that cnidarian eyes originated at least eight times, with complex, lensed-eyes having a history separate from other eye types. Our results show eyes evolved repeatedly from ancestral photoreceptor cells in non-bilaterian animals with simple nervous systems, co-opting existing precursors, similar to what occurred in Bilateria. Now, we are leveraging single cell analysis tools to measure gene expression across photoreceptor cells from jellyfish with eyes that originated separately to understand their evolutionary history and interplay with eye origins.