In his first appearance in the 1994 film as Colonel Jack O'Neill, the character leads the first team to go through the Stargate on a reconnaissance mission.

In the first seven seasons of the show, Colonel Jack O'Neill, recalled from retirement after the first film, is the leader of the team SG-1, a part of the Stargate Program, whose goal is to explore the galaxy and defend against alien threats.

The character's absence from the show was explained by yet another promotion, to the position of head of the Department of Homeworld Security, as a major general.

Jack O'Neill is a United States Air Force colonel with experience in special operations before joining the Stargate Program.

O'Neill possesses the ATA gene, and thus is able to operate the Ancient weapons chair and save Earth from Anubis's fleet.

[12] O'Neill reappears as a lieutenant general in Stargate Universe with Nicholas Rush, where he is recruiting Eli Wallace into the Icarus Project.

With help from the Ancient Communication Stones, Everett Young body swaps with Colonel David Telford to tell O'Neill about a dire situation in which they find themselves.

[14] Although Anderson was never a real fan of the science fiction genre, he believed the original feature film to be a good vehicle for a series.

[15] Anderson agreed to become involved with the project if his character was allowed significantly more comedic leeway than Kurt Russell's character in the feature film, shown especially Anderson's flippant and utter disregard for appropriate military protocol and decorum over the series, which contrasted Russell's "by the book" adherence to protocol.

Fans have speculated that the transition is due to Russell's O'Neill still being deeply traumatised by the recent death of his son, while Anderson's has overcome the worst of his issues even if he makes it clear he will never forget his loss.

[17] When Anderson left the show as a main character in the eighth season, the producers were talking about ending the series.

Executive producer Brad Wright stressed the importance of O'Neill's presence in the Stargate universe even after the character went on hiatus during the last two seasons of SG-1 when Anderson took a leave from regular acting.

[20] Anderson was nominated in the category for "Best Male Performance in a 2008 Science Fiction Film, TV Movie, or Mini-Series" at the Constellation Awards in 2009 for his work in Stargate: Continuum (2008), where he reprised his role as O'Neill.