Kalmus is a surname. Notable people with the surname include:
Ain Kalmus (1906–2001), Estonian writer and theologian Alfred Kalmus (1889-1972), Austrian-British music publisher Edwin F. Kalmus (1893-1989), American music publisher George Kalmus (born 1935), British particle physicist Herbert Kalmus (1881-1963), American scientist and engineer Marion Kalmus, British artist Natalie Kalmus (1882-1965), American Technicolor color supervisor Peter Kalmus (artist) (born 1953), Slovak artist and activist Peter Kalmus (climate scientist) (born 1974), American climate scientist Peter Kalmus (physicist) (born 1933), British particle physicist