Eystein Karl Mørner Paasche (17 September 1932 – 27 November 2016) was a Norwegian botanist.
He was born in Oslo as a son of literary historian Johan Fredrik Paasche.
He was appointed professor of marine botany at the University of Oslo in 1973.
He was a fellow of the Norwegian Academy of Science and Letters.His wife Rosamaria AlegrÃa Paasche, "Rosita", died the next day.