A hundred years have passed since the description of the genus Dunaliella, the unicellular green alga which is responsible for most of the primary production in hypersaline environments worldwide. The present paper provides an historical survey of research on Dunaliella, from the early work in the 19th century to the thorough taxonomic studies by Teodoresco, Hamburger, Lerche and others from the beginning of the 20th century onwards. It attempts to trace the origin of some of the most important breakthroughs that have contributed to our present understanding of this alga that plays such a key role in many hypersaline environments.