M81

M81 or M-81 may refer to:


 * M-81 (Michigan highway), a state highway in Michigan
 * McDonnell-Douglas MD81
 * Messier 81, a spiral galaxy in the constellation Ursa Major, also known as NGC 3031 or Bode's Galaxy
 * U.S. Woodland, a camouflage pattern colloquially known as "M81"