Mullin is a surname, and may refer to
- Chris Mullin (basketball)
- Chris Mullin (politician), British Labour Party Member of Parliament
- George Mullin (baseball) (1880–1944), baseball pitcher
- George Mullin (VC) (1892–1963), American recipient of the Victoria Cross during World War I
- Herbert Mullin, American serial killer
- Hugh P. Mullin, Philippine-American War Medal of Honor recipient
- Jack Mullin
- Joseph Mullin (1811–1882), New York lawyer and politician
- Mike Mullin
- Willard Mullin
- Glenn Mullin (author)