O13

O13 or O-13 may refer to:
 * Curtiss O-13 Falcon, an observation aircraft of the United States Army Air Corps
 * HNLMS O 13, a submarine of the Royal Netherlands Navy
 * Oxygen-13, an isotope of oxygen
 * Pyramid O-13, the hypothesized mortuary temple of Itzam Kʼan Ahk II
 * USS O-13 (SS-74), a submarine of the United States Navy