M100 or M-100 may refer to:

;Aviation

  • M-100 (rocket), a two-stage Soviet sounding rocket
  • Miles Student (M.100), a lightweight trainer aircraft
  • Mitsubishi SpaceJet M100, a regional jet aircraft
  • DJI Matrice 100, a Chinese industrial drone
  • Klimov M-100, a Soviet version of the Hispano-Suiza 12Y aeroengine

;Computing

  • TRS-80 Model 100, an early portable computer
  • Palm m100 series, a popular lower cost version of the Palm Pilot

;Road and Rail

  • M-100 (Michigan highway), a north–south state trunkline highway in the U.S. state of Michigan
  • M100 (Cape Town), a metropolitan route near Cape Town, South Africa
  • M100 (New York City bus), a New York City Bus route in Manhattan
  • M100, the second version of the Jeep trailer
  • Effa M100, the Brazilian name for the Changhe Ideal automobile
  • M100 Elan, a model of the Lotus Elan automobile
  • Mercedes-Benz M100 engine, a 6.3/6.9 liter SOHC V8 automobile engine
  • HKL Class M100, a metro train of Helsinki Metro

;Other

  • M-100 (explosive), a pyrotechnic device
  • M100, the magnetoencephalographic equivalent to the N100 large, negative-going evoked potential measured by electroencephalography
  • Messier 100, a grand design spiral galaxy
  • Calico M100, a novel .22 caliber semi-automatic carbine
  • Canon EOS M100, an mirrorless camera from Canon
  • Masters athletics, an age group for athletes aged 35+