Mark I
- Aptera Motors
- Arabic numerals
- British Railways Mark 1
- Colossus Mark I
- Deep Purple
- Detroit People Mover
- Ferranti Mark 1
- GE BWR
- Harvard Mark I
- Innovia Metro
- Iron Man's armor
- Little Boy
- Lovell Telescope
- MK1 (disambiguation)
- MKI (disambiguation)
- Manchester Mark 1
- Mark 1
- Mark I (detector)
- Mark I Fire Control Computer
- Mark I NAAK
- Mark I tank
- Mark I trench knife
- Mark One (disambiguation)
- Mesa Boogie Mark Series
- Mk 1 Underwater Defense Gun
- Mk 1 grenade
- Mk I Mini
- Patriarch Mark I
- Patrol Boat, River
- Perceptron
- Roman numerals
- SkyTrain (Vancouver)
- Supermarine Spitfire variants part one
- Tomorrow Never Knows
- Toronto
- Visual inspection