Hank Landry (Stargate)

Spanning ten years and several films, Stargate SG-1 developed an extensive and detailed backdrop of diverse characters. Many of the characters are members of alien species discovered while exploring the galaxy through the Stargate, although there are an equal number of characters from offworld human civilizations. While Stargate SG-1, Stargate Atlantis and Stargate Universe are separate shows, they take part in the same fictional universe, so no character is internally show-specific.

Except for the commanders of the top-secret Stargate Command military base (SGC), all main characters of Stargate SG-1 are members of the SG-1 team, the primary unit of the SGC in the show. SG-1's duties include first contact, reconnaissance and combat, diplomacy, initial archaeological surveying, and technological assessment. The composition of SG-1 changes several times during the series run and varies in several alternative universes.

Jack O'Neill is a USAF Colonel (later Brigadier General, Major General and then Lt. General) who led the original mission through the Stargate in Stargate. He is played by Kurt Russell in the film, and by former MacGyver actor Richard Dean Anderson in a regular role in seasons 1–8, and in a recurring role in seasons 9–10, also Michael Welch played young Colonel O'Neill in episode "Fragile Balance". He also appears in Stargate: Continuum, and in seasons 1 and 3 of Stargate Atlantis. Colonel O'Neill is the leader of the SG-1 team in the first seven seasons, and takes charge of Stargate Command after his promotion to Brigadier General at the beginning of season 8. He is promoted to Major General at the beginning of season 9, and is reassigned to Washington, D.C., then makes sporadic appearances in the final episodes of season one of Stargate Universe.

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Wikipedia