John Sheppard is a fictional character

Fictional character

A character is the representation of a person in a narrative work of art . Derived from the ancient Greek word kharaktêr , the earliest use in English, in this sense, dates from the Restoration, although it became widely used after its appearance in Tom Jones in 1749. From this, the sense of...

 in the Canadian-American military science fiction

Military science fiction

Military science fiction is a subgenre of science fiction in which the principal characters are members of a military service and an armed conflict is taking place, normally in space, or on a planet other than Earth...

 television series Stargate Atlantis

Stargate Atlantis

Stargate Atlantis is a Canadian-American adventure and military science fiction television series and part of MGM's Stargate franchise. The show was created by Brad Wright and Robert C. Cooper as a spin-off series of Stargate SG-1, which was created by Wright and Jonathan Glassner and was itself...

, a science fiction show about a military team exploring the galaxy via a network of alien transportation devices. Portrayed by Joe Flanigan

Joe Flanigan

Joe Flanigan is an American television actor best known for his portrayal of the character Major/Lt. Colonel John Sheppard in Stargate Atlantis.-Early life:Flanigan was born Joseph Dunnigan III in Los Angeles, California...

, Sheppard holds the military rank

Military rank

Military rank is a system of hierarchical relationships in armed forces or civil institutions organized along military lines. Usually, uniforms denote the bearer's rank by particular insignia affixed to the uniforms...

 of Lieutenant Colonel

Lieutenant colonel

Lieutenant colonel is a rank of commissioned officer in the armies and most marine forces and some air forces of the world, typically ranking above a major and below a colonel. The rank of lieutenant colonel is often shortened to simply "colonel" in conversation and in unofficial correspondence...

 in the series and is the second-in-command

Second-in-command

The Second-in-Command is the deputy commander of any British Army or Royal Marines unit, from battalion or regiment downwards. He or she is thus the equivalent of an Executive Officer in the United States Army...

 of the Atlantis Expedition after the death of Marshall Sumner (Robert Patrick

Robert Patrick

Robert Hammond Patrick, Jr. is an American actor, known for his leading and supporting roles in a number of films and television shows....

) in "Rising

Rising (Stargate Atlantis)

"Rising" is the pilot episode for season one of the military science fiction television series Stargate Atlantis, a Canadian-American spin off series of Stargate SG-1. The episodes were written by executive producers Brad Wright and Robert C. Cooper, the episodes were directed by Martin Wood...

".

Sheppard and Rodney McKay

Rodney McKay

Doctor Meredith Rodney McKay, Ph.D, is a fictional character in the Canadian-American Sci-Fi Channel television series Stargate SG-1 and Stargate Atlantis, two military science fiction television shows about a military team exploring two galaxies via a network of alien transportation devices...

 (David Hewlett

David Hewlett

David Ian Hewlett is an English-born Canadian actor best known for his role as Dr. Meredith Rodney McKay on the science fiction television shows Stargate SG1 and Stargate Atlantis.-Early life:...

) are the only characters to appear in every episode of the series.
John Sheppard was an experienced and a talented US Air Force Officer

Officer (armed forces)

An officer is a member of an armed force or uniformed service who holds a position of authority. Commissioned officers derive authority directly from a sovereign power and, as such, hold a commission charging them with the duties and responsibilities of a specific office or position...

 in Afghanistan

Afghanistan

Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...

, though his reputation was somewhat tarnished when he disobeyed a direct order in an unsuccessful attempt to save the lives of several US servicemen.