Jens Otto Harry Jespersen was a Danish linguist who worked in foreign-language pedagogy, historical phonetics, and other areas, but is best known for his description of the grammar of the English language.
Jespersen was a professor of English at the University of Copenhagen from 1893 to his retirement in 1925. Jespersen was Dean of the Faculty of Arts from November 1904 to November 1906; and Rector (vice-chancellor, or president) of the university from November 1920 to November 1921.