O5 or O-5 may refer to: * The "Outreach 5", emerging economies in the

Heiligendamm Process The Heiligendamm process is an initiative that will institutionalize high-level dialogue between the G8 and the five most important emerging economies, known as the O5 (Outreach 5): China, Mexico, India, Brazil and South Africa. The framework w ...

: China, Mexico, India, Brazil and South Africa * A symbol for the anti-Nazi Austrian Resistance, where the 5 stands for E and OE is the abbreviation of Österreich * USS ''O-5'' (SS-66), a 1917 O-class submarine * HNLMS ''O 5'', a 1913 ''O 2'' class submarine of the Royal Netherlands Navy * SM ''UC-99'', a U-boat renamed O-5 for Japanese service from 1920 to 1921 * Douglas World Cruiser, also designated as Douglas O-5 * De Havilland Canada Dash 7, also designated as De Havilland Canada O-5 * LNER sub-class O4/5, a subclass of the LNER Class O4, locomotive class * O-5, the pay grade for the following officer ranks in the U.S. uniformed services: **

Lieutenant colonel Lieutenant colonel ( , ) is a rank of commissioned officers in the armies, most marine forces and some air forces of the world, above a major and below a colonel. Several police forces in the United States use the rank of lieutenant colone ...

in the Army, Marine Corps, Air Force, and Space Force **

Commander Commander (commonly abbreviated as Cmdr.) is a common naval officer rank. Commander is also used as a rank or title in other formal organizations, including several police forces. In several countries this naval rank is termed frigate captain. ...

in the Navy, Coast Guard, Public Health Service Commissioned Corps, and NOAA Commissioned Officer Corps *

Otoyol 5 ( en, Motorway 5), named the Gebze-Orhangazi-İzmir Motorway ( tr, Gebze-Orhangazi-İzmir Otoyolu) and abbreviated as O-5, is a toll motorway in Turkey. Since being completed in 2019, it connects the Istanbul metropolitan area with İzmir, via ...

, a toll motorway in Turkey * The

time-displaced X-Men The X-Men are a superhero team appearing in American comic books published by Marvel Comics, first appearing in ''The X-Men'' #1 by artist/co-plotter Jack Kirby and writer/editor Stan Lee in 1963. Although initially cancelled in 1970 due to lo ...

, also called "The Original 5" * The senior “overseer” position in the

SCP Foundation The SCP Foundation is a fictional secret organization documented by the collaborative-writing wiki project of the same name. Within the website's shared universe, the Foundation is responsible for capturing, containing, and studying various p ...

See also