O13 or O-13 may refer to: Curtiss O-13 Falcon, an observation aircraft of the United States Army Air Corps , 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 , a submarine of the United States Navy
See also 013, a music venue in Tilburg, the Netherlands