Star Trek Canon Special Note
Not everything listed in the origin is Canon. That is because only television shows and movies are considered canon for Star Trek. This being a comic website there are many things here that are not canon. So unless it is contradicted in film it should be listed as part of the character biography.
Kira Nerys was born on the planet Bajor during the occupation of Bajor by the Cardassians. She became a member of the resistance and the Bajoran militia after the occupation ended. In the militia she was granted the rank of major, and was appointed as a liaison officer to the Federation and posted to the space station Deep Space Nine (DS9). In this position she earned the trust of Commander Benjamin Sisko, although she was quite abrasive to him at first.
Kira was created for the television show Star Trek: Deep Space Nine. She was created when the actress who played Ro Laren refused to sign on to a series.
Kira was abrasive toward Sisko at first and argued with his regularly she even went over his head at times but Sisko ended that very quickly. Kira became a hero when she rescued Bajor's most famous resistance fighter only to have him take her job on the station due to an attempted coup. After the coup was suppressed she went back to the role of second in command on DS9. While on Deep Space Nine Kira had a couple romances that ended poorly for her. She fell in love with Vedak Bareil Antos only to have his life taken from her. She also fell in love with her ex-resistance leader only to have that end as well. What Kira never saw was that Odo, the ship's security Officer, was madly in love with her, but could not find the right time or way to tell her.
Kira eventually finds out about Odo during a mission with a time paradox. In order to save the life of Kira a much older Odo sabotages the U.S.S. Defiant snuffing over a hundred people out of existence. When she finds out things become even more awkward for Odo and Kira. They stayed the closest of friends however and eventually Kira saw that her love was right in front of her eyes the whole time. Kira and Odo finally become a couple only to lose him as well at the end of the Dominon was when Odo goes back to his planet for an indeterminate time.
During the Dominon war Kira was promoted to the rank of Colonel and even made a Federation officer with the rank of commander. The later adjustment was due to her helping the Cardassins become resistance fighters. The irony was not lost on anyone. At the end of the war Kira assumed command of DS9 when Sisko entered the wormhole. Kira also lost her dear friend Jadzia Dax when her long time enemy Dukat killed her while she was praying to the Bajoran prophets.
The evil mirror version of Kira commands the Bajorian sector of the Klingon/Cardassian Alliance. She was attracted to her alternate version self, Mirror-Sisko, and Mirror Ezri.