Hanns Kreisel (16 July 1931 – 18 January 2017) was a German mycologist and professor emeritus. He was born in Leipzig in 1931. Kreisel was a professor at the University of Greifswald. His field was the classification of fungi, where he has studied this group of organisms not only in Germany but in almost all continents, as in Brazil, Seychelles, Vietnam, Cuba and Syria. He had succeeded with his first collaboration to develop a scientifically sound and current fungal flora of Yemen. Kreisel also specialized in the fungal groups of gut fungi.