Job Bicknell Ellis (January 21, 1829 – December 30, 1905) was a pioneering North American mycologist known for his study of the Ascomycetes, especially the grouping of fungi called the Pyrenomycetes (known today as the Sordariomycetes).
Born and raised in New York, he worked as a teacher and farmer before developing an interest in mycology.
He collected specimens extensively, and together with his wife, prepared 200,000 sets of dried fungal samples that were sent out to subscribers in series between 1878 and 1894.
Together with colleagues William A.
Kellerman and Benjamin Matlack Everhart, he founded the Journal of Mycology in 1885, forerunner to the modern journal Mycologia.
He described over 4000 species of fungi, and his collection of over 100,000 specimens is currently housed at the herbarium of the New York Botanical Gardens.
Ellis had over 100 taxa of fungi named in his honor.