Apicomplexans are obligate intracellular parasites that have evolved from a free-living, phototrophic ancestor. The discovery of corallicolids, a clade of coral-infecting apicomplexans that retain chlorophyll biosynthesis genes, provided a unique window into this evolutionary transition. Here we describe new corallicolid diversity from a global survey of coral-associated eukaryotes, expanding our understanding of this important group and its evolutionary relationship to other apicomplexans.