Simon O'Neill
a Number Four who chose his family
Simon O'Neill was a Number Four who infiltrated Colonial society as a fleet medic. After the Fall of the Twelve Colonies he chose his family over his model and died rather than carry out a Number One's terror plot.
Simon O'Neill was a Number Four who infiltrated Colonial society ahead of the Fall of the Twelve Colonies. Posing as a fleet medic, he came to value the family he had built over his model, and after the attack he chose death over carrying out a Number One's terror plot aboard the Cybele. (Battlestar Galactica: The Plan)
Biography#
In his service, Simon lived on Gemenon, taking on the role of a medic in the Colonial fleet, where he fell in love with Giana and married her. When the attack began, Simon chose to flee with his stepdaughter rather than resurrect, and boarded the Cybele. The two were later reunited with Giana, who had won a place on a Raptor leaving Caprica in a lottery for the last seats. (Battlestar Galactica (miniseries); Battlestar Galactica: The Plan)
Conflict and death#
Simon's commitment to his family became a serious problem to a Number One in the fleet, and he tried to avoid conscription into the Number One's terror cell. Though he offered to kill people in his role as a medic, this was unacceptable to One, who wanted more extreme actions. The fear of harming his family weighed heavily on Simon, and his relationship with Giana deteriorated. (Battlestar Galactica: The Plan)
Finally, Simon conceded and agreed to blow up the Cybele, but One was unwilling to protect his family. Instead, Simon fashioned a smaller explosive charge to destroy an airlock, flushing himself into space and killing himself. Out of range, Simon did not resurrect. (Battlestar Galactica: The Plan)
Simon left a suicide note, and his death was treated as a suicide. Giana only learned what he had been when she saw a photograph of another Number Four, and Galen Tyrol comforted her by pointing out that Simon had killed himself rather than act against the Fleet. (Battlestar Galactica: The Plan)
Frequently asked questions
- Who was Simon O'Neill?
- Simon O'Neill was a Number Four who infiltrated Colonial society ahead of the Fall of the Twelve Colonies. He lived on Gemenon as a medic in the Colonial fleet, where he fell in love with and married a woman named Giana.
- What happened to Simon after the Fall?
- When the attack began, Simon chose to flee with his stepdaughter rather than resurrect, boarding the Cybele. The two were later reunited with Giana, who had been rescued from Caprica.
- How did Simon die?
- A Number One in the fleet pressured Simon to join his terror cell and destroy the Cybele. Unwilling to harm his family, Simon instead fashioned a smaller charge to destroy an airlock, flushing himself into space. Out of range, he did not resurrect.
Sources
- EpisodeBattlestar Galactica (miniseries), Miniseries, Parts 1 and 2 (2003)
- FilmBattlestar Galactica: The Plan, Universal Cable Productions, 2009
Spotted a factual error or a primary source we missed? Email a correction. Every flagged claim gets reviewed.
Followed from this entry

Galen Tyrol
Chief Petty Officer Galen Tyrol kept Galactica's flight deck running through the long flight from the Colonies, a respected and fiercely protective deck chief who learned that he was in fact one of the Final Five Cylons, descended from the Thirteenth Tribe.

Number Four
Number Four, also known as Simon O'Neil, was a model of humanoid Cylon created by the Final Five after the Cylon War. Often serving as doctors and medics, the Fours sided with the Ones and Fives during the Cylon Civil War.

Number One: John Cavil
Number One, called John, was the first humanoid Cylon the Final Five built. He wiped out the entire Number Seven line and had the Five's memories erased.

Caprica: the Colonial capital
Caprica was the richest of the Twelve Colonies, seat of the Colonial government, and the world where the Cylons were built. The Cylon attack destroyed it.

Cybele: the freighter that fled Gemenon
The Cybele was a Colonial freighter that survived the Fall of the Twelve Colonies. Escaping Gemenon in the opening hours of the attack, it joined the fleet that gathered near Caprica and carried among its passengers a hidden humanoid Cylon.

Fall of the Twelve Colonies
A single day of Cylon attack killed billions of people across Colonial space. Barely fifty thousand escaped in a refugee fleet.
Mentioned in4 entries
Battlestar Galactica: The Plan, the Cylon side of the story
The Plan is the 2009 TV film that replays the attack and the first two seasons through the eyes of two copies of Cavil. Here's what happens, what it adds, and whether you should watch it.
Cybele: the freighter that fled Gemenon
The Cybele was a Colonial freighter that survived the Fall of the Twelve Colonies. Escaping Gemenon in the opening hours of the attack, it joined the fleet that gathered near Caprica and carried among its passengers a hidden humanoid Cylon.
Every Cylon Model in Order, by Number: One to Eight and the Final Five
All twelve humanoid Cylon models from the reimagined Battlestar Galactica, in order by number, from Cavil and Leoben to Saul Tigh and Tory Foster. Who each one was, the copies that mattered, what they wanted and how their story ended.
Giana O'Neill: the deck hand who survived the Fall
Giana O'Neill was a human refugee who survived the Fall of the Twelve Colonies by winning a lottery seat aboard a Raptor. She enlisted in the Colonial Fleet as a deck hand and was later reunited in the fleet with the husband she had believed lost, unaware that he was a humanoid Cylon.
Get new articles in your inbox
No spam. New lore drops, canon conflicts, and deep dives only when they’re worth reading.
Some links on Lore Fortress are affiliate links. If you buy through them we earn a small commission at no extra cost to you.