Otto Emil Plath (April 13, 1885 – November 5, 1940) was a German American author, a professor of biology and German at Boston University, and an entomologist, with a specific expertise on bees.
He was the father of American poet Sylvia Plath, Warren Plath, and the husband of Aurelia Plath.
He wrote the 1934 book, Bumblebees and Their Ways.
He is notable for being the probable subject of one of his daughter's most well-known poems, Daddy.