Jack O'Neill

Jack O'Neill was the leader of SG-1 from its inception in 1997 until he was promoted to Brigadier General in 2004, and placed in command of Stargate Command. He commanded the SGC from 2004 to 2005 and is currently a Lieutenant General and head of Homeworld Security. He was on the original expedition to Abydos with Daniel Jackson. He's a brave, irreverent, protective, skeptical, sometimes short-tempered man; an atypical but successful military leader. Together with his team, he's a bonafide hero of Earth. His service number is 69-4-141.

His personal history is troubled: shortly before traveling through the Stargate for the first time his son was killed while playing with his pistol and, in the aftermath of this tragedy, he separated from his wife Sara O'Neill. His professional life has been adventurous. He has hinted at some of the operations in his years in the special forces: covert operations in East Germany and Iraq (during the Gulf War) have been mentioned. He was born on October 20, 1952 in Chicago, Illinois, USA (SG1: "Fragile Balance", "Cold Lazarus", "Family"). His father-in-law described him as being an Irishman, confirming that he is of Irish descent. (SG1: "Cold Lazarus")

He has feelings for Samantha Carter that seem to be reciprocal; they were once both forced to admit it to avoid being labeled as Zatarcs (SG1: "Divide and Conquer"). Because this kind of relationship is forbidden in the Air Force, he has never pursued a relationship with her, keeping well within the rank border. He even encouraged her during her engagement to Pete. He had a relationship with Kerry Johnson, but she felt there was something deeper between him and Sam. Kerry told him to retire but he didn't take her advice. She goes on saying they were making big error if they let military rules stop their feelings(SG1: "Threads"). Jacob Carter has hinted at knowing their feelings, as have Teal'c and Gen. Hammond. (SG1: "Paradise Lost", "Grace"). When a wedding was proposed by Vala in her search for an ending scenario for a 'Stargate movie', neither of them answered.(SG1: "200")

When Teal'c once stated he was a brother to him, Jack reminded him that Teal'c was twice his age; Teal'c conceded that he was a very young brother, then, though it had no importance as he was trying to comfort him while Sam was missing (SG1: "Grace").

Jack has a tendency to not lock his house when leaving, which has caused some unwanted visits. (SG1: "Full Alert", "Citizen Joe")

Jack O'Neill also naturally possesses the Ancient Technology Activation Gene.

Jack has a very dry sense of humor and is impatient with complicated explanations. However, in a conversation with Lt. Col. Samantha Carter, he explains that he is worried about her because she has not tried to baffle him with scientific babble for a few days. When he is asked a scientific question he doesn't know the answer to, he often jokingly answers with "magnets," or some variation of the term. As stated by Cassandra, Jack pretends he's not as smart as he really is. (SG1: "Affinity", "Rite of Passage").

O'Neill was originally born in Chicago, but he moved to Minnesota at some point. (SG1: "Children of the Gods", "The Fifth Man")

O'Neill likes cake, and his favorite color is peridot. (SG1: "Heroes, Part 1")

The Asgard showed great fondness toward him. Loki even stated that: "O'Neill is legendary" hinting the Asgard's view of him. To them, he led his people through the galaxy and proved to them that the Tau'ri were well on their way to be the "Fifth Race". He also downloaded, twice, the knowledge of Ancients and created the Replicator disruptor which save their planet. When Earth was accused of stealing over Asgard, Nox and the Tollan's technology, the Asgard chose him alone to prove his people weren't culprits. (SG1: "Fair Game", "Shades of Grey", "The Fifth Race", "Lost City", "New Order")