Number Eight is a female humanoid Cylon model on the television series Battlestar Galactica, a reimagining of the classic show of the same name. She is portrayed by Grace Park. Two prominent Number Eight copies serving as Galactica pilots are Sharon Valerii and Sharon Agathon, using the call signs "Boomer" and "Athena", respectively. The call signs for both Sharons hail back to the original Battlestar Galactica series. Boomer was the name (not the call sign) of a Viper pilot character played by Herbert Jefferson, Jr., while Athena was the name of Commander Adama's daughter.

Notable copies
Cylon models Six and Eight are the most common in the series. Many Number Eight copies have been seen in various roles, including leadership positions; two are featured as central characters — Boomer and Athena.

Sharon "Boomer" Valerii

Lieutenant Junior Grade Sharon "Boomer" Valerii is a Cylon sleeper agent programmed with false memories of being raised in the mining colony Troy. Before the mini-series, Boomer and Galen Tyrol are romantically involved, which is against military protocol due to their ranks. Her programming leads her to black out and sabotage the Galactica on several occasions, which Tyrol unwittingly abets by hiding evidence implicating her. In "Kobol's Last Gleaming", Commander Adama sends Boomer on a mission to destroy the Cylon basestar orbiting Kobol; and after her return, she shoots Adama twice in the chest, putting him in a coma and revealing her nature to the crew. While Boomer is in the brig, Gaius Baltar manipulates her into revealing how many other Cylons are hidden in the fleet. While Boomer is being transported from the brig, Cally shoots and kills her.

In  "Downloaded", Boomer's consciousness is downloaded into a new body in Cylon-occupied Caprica. She resists being identified with the Cylon cause and tries to persuade the Cylons to reduce hostility against humans. In "The Eye of Jupiter", Boomer attempts to care for Athena's hybrid child Hera on the Cylon base ship, where the child ended up after the New Caprica evacuation. In a conflict with the visiting Athena over whether the humans negotiated in good faith, Boomer is killed by Caprica Six for endangering the child.

After resurrecting again, Boomer develops a relationship with John Cavil, a Number One who embraces his machine nature and sees human traits as a weakness. Cavil enlists Boomer's support when the Cylon models become deadlocked in a vote over whether the Raiders should be lobotomized. Boomer turns against Cavil during the Colonial assault on the Cylon colony. After returning Hera to Athena and Helo, who were part of the boarding party, Boomer allows Athena to gun her down as penance for her actions.

Sharon "Athena" Agathon 

A self-aware Number Eight who impersonates the original Sharon and helps Karl 'Helo' Agathon to further a Cylon experiment that relies on having him fall in love with her, and to kill him eventually by the experiment's conclusion. However, she eventually falls genuinely in love with Helo and tries to help him escape, during which he discovers her true identity. Sharon reveals that she is pregnant with his child, the first known successful attempt at a Cylon/human hybrid. Sharon uses her knowledge of the Tomb of Athena on Kobol as leverage to avoid immediate execution and consistently demonstrates her loyalty by defending the group from Cylon ambushes. Sharon's reunion with the Galactica personnel is tense due to Boomer's history with them, but she makes it clear that she is a separate consciousness and a different person from Boomer. 

Upon finding out about Sharon's pregnancy, President Roslin orders it terminated but rescinds her decision when the fetal blood successfully cures her terminal cancer. Sharon gives birth to her child prematurely and names her Hera. The Colonial administration decides it is too dangerous to let a hybrid child be raised by a Cylon mother, so they fake the child's death and rehome her with a human mother. Despite the strain this puts on Sharon's loyalty, she continues to help the Galactica.

Sharon and Helo are married in the year-long gap in events between Season 2 and Season 3, and, having earned the full trust of Admiral Adama, Sharon is sworn in as an officer in the Colonial Fleet at Boomer's rank of Lieutenant JG. She is sent back to New Caprica as the liaison between the Galactica fleet and the resistance effort, and, due to the inability of the Centurions to recognize individuals within the humanoid Cylon models, is able to infiltrate the Cylon base and steal the keys for the civilian ships. After the successful rescue mission, Sharon receives a new call sign: Athena, after the goddess of warfare and wisdom.

During Colonial negotiations with the Cylons, Athena and Helo learn their daughter is still alive on a Cylon ship. Athena travels to the ship and retrieves her daughter, prompting a conflict with Boomer in which Boomer is killed by Athena for endangering Hera.

See also
Woman warrior
List of women warriors in folklore

References

External links
 Number Eight at Battlestar Wiki

Cylons
Fictional fighter pilots
Fictional cyborgs
Fictional gynoids
Fictional clones
Fictional female lieutenants
Fictional female secret agents and spies
Fictional sleeper agents
Fictional characters with death or rebirth abilities
Television characters introduced in 2003
Fictional space pilots