03
03 may refer to:
- The year 2003, or any year ending with 03
 - The month of March
 - 3 (number)
 
Music
- 03 (Twelve album), 2007
 - 03 (Urban Zakapa album), 2013
 
Other uses
- 03 numbers, a non-geographic telephone number range in the UK
 - The telephone area code for the South Island of New Zealand.
 - The number of the French department Allier
 - The occupational field designator for U.S. Marine Corps Infantry
 - Tokyo Metro 03 series
 - iCar 03, an electric compact crossover SUV
 - Lynk & Co 03, a compact executive sedan