M120 or M-120 may refer to:

• M120 mortar, a mortar in United States Army infantry and armor units
• M-120 (Michigan highway), a state highway in Michigan
• Mercedes-Benz M120 engine, a V12 automobile piston engine

• William Allan Jones, Jr.
• William Allan of Glen
• William Allan Rodda
• William Allan (trade unionist)
• William Allan Wulf
• William Allchin
• William Allen (Black Quaker minister)
• William Allen Casselman
• William Allen Dixon
• William Allen (Irish politician)
• William Allen (Montana politician)
• William Allen Montgomery
• William Allen (Niehaus)
• William Allen (Quaker minister)
• William Allen (scientist)
• William Allen White House
• William Alley (athlete)
• William Allison (Assemblyman)
• William Allison (Assenblyman)
• William Allison Shimer
• William Allison (State Representative)
• William Alonzo Barber
• William A. Losier
• William Alphonsus Gunn
• William Alton Schoech