John Cassin was an American ornithologist from Pennsylvania. He worked as curator and Vice President at the Philadelphia Academy of Natural Sciences and focused on the systemic classification of the Academy's extensive collection of birds. He was one of the founders of the Delaware County Institute of Science and published several books describing 194 new species of birds. Five species of North American birds, a cicada, and a mineral are named in his honor.

Magicicada cassini, known as the 17-year cicada, Cassin's periodical cicada or the dwarf periodical cicada, is a species of periodical cicada. It is endemic to North America. It has a 17-year life cycle but is otherwise indistinguishable from the 13-year periodical cicada Magicicada tredecassini. The two species are usually discussed together as "cassini periodical cicadas" or "cassini-type periodical cicadas." Unlike other periodical cicadas, cassini-type males may synchronize their courting behavior so that tens of thousands of males sing and fly in unison. The species was first reported to the Academy of Natural Sciences of Philadelphia by Margaretta Morris in 1846. In 1852, the species was formally described by J. C. Fisher and given the specific name cassini in honour of John Cassin, an American ornithologist, whose own report was included by Fisher in his publication.