Stephanie Bronwyn Flynn was an ex-wife of NCIS Special Agent Leroy Jethro Gibbs.
In the Season 1 episode, Hung Out to Dry (episode), NCIS Medical Examiner Donald Mallard related that Gibbs's third ex-wife gets drunk on their anniversary and calls him excessively. Ducky also relates that he initially introduced the two.
In The Curse (episode), Ducky also told Gibbs that four years prior, Gibbs's third ex-wife hit him in the head with a baseball bat. Ducky treated the injury and also happened to be performing an autopsy on a deceased Marine who apparently had been buried in an ant-hill up to his neck at the time.
In the Season 5 episode, Ex-File (episode), it was revealed that Gibbs and Stephanie spent a year in Moscow together. Stephanie believed that Gibbs was romantically involved with Jenny Shepard prior to their marriage. Stephanie was a witness in the death of Captain Trent Reynolds U.S.M.C., and during the course of the investigation Stephanie requested that Jethro be removed from the case, a request Gibbs's boss, NCIS Director Jennifer Shepard denied.
Despite this, at the conclusion of the episode, Stephanie returned his dog tags and Gibbs walked her out to her car. Stephanie lamented her experience with men, Gibbs felt enough affection for her to attempt to comfort her by saying Gibbs "Me. Us. It's not your fault". Stephanie: "It wasn't anyone's fault, but at least we'll always have Moscow," and they parted amicably.
It could also be presumed that this was also responsible for permanently ending Gibbs's own relationship with Lieutenant Colonel Hollis Mann.