Roberto Esser dos Reis, is a Brazilian ichthyologist, professor and Curator of Fishes at the Pontifical Catholic University of Rio Grande do Sul.
Most of his research as an ichthyologist regards different types of South American catfish.
He is also chair for South America of the Freshwater Fish Specialist Group, Species Survival Commission, and advises the IUCN on the biological aspects of the conservation of threatened species.
Reis authored more than 120 original journal papers, and four books.
Reis is Chief Editor of the Checklist of Freshwater Fishes from Central and South America (CLOFFSCA), and past President of the Brazilian Ichthyological Society.