O23 or O-23 may refer to:
- HNLMS O 23, a submarine of the Royal Netherlands Navy
- Osim International, a Singaporean company
- Oxygen-23, an isotope of oxygen
- Ranchaero Airport, in Butte County, California, United States; assigned FAA LID O23 until 2009
- Thomas-Morse O-23, an observation aircraft of the United States Army Air Corps
Topics referred to by the same termThis disambiguation page lists articles associated with the same title formed as a letter–number combination.If an internal link led you here, you may wish to change the link to point directly to the intended article. Category: