Kasidy Danielle Yates-Sisko was a female Human and freighter captain in the 24th century United Federation of Planets. She founded Kasidy Yates Interstellar Freights and commanded the SS Xhosa on freight runs, initially as an independent transporter, but later for the Bajoran Ministry of Commerce. She married Starfleet Captain Benjamin Sisko and had a child with him.
Yates was introduced to Benjamin Sisko by his son Jake, who felt that his father needed a girlfriend. Yates and Sisko shared a common interest in baseball, and Yates' youngest brother played for the Pike City Pioneers on Cestus III. Yates later played for Sisko's baseball team, the Niners, against the Logicians. (DS9: "Family Business", "The Way of the Warrior", "Take Me Out to the Holosuite")
As their relationship went on, Yates decided to take an opportunity to work for the Bajorans where her primary missions were to export cargo from Bajor to its colonies. This allowed her to move to Deep Space 9 permanently. However, she also used this opportunity to smuggle cargo to the Demilitarized Zone for the Maquis.
In 2372, she unwittingly aided the Maquis in the theft of twelve industrial replicators that were intended for Cardassia. Yates was suspected of working for the Maquis by Odo and by Deep Space 9's head of Starfleet security Michael Eddington, who was himself secretly working for the Maquis at the time. Yates was tricked into taking her ship on another smuggling run, drawing a suspicious Captain Sisko and the USS Defiant into the Badlands long enough for Eddington to defect to the Maquis with the replicators. Yates accepted sole responsibility for her ship's smuggling activities, and after allowing her crew to rejoin the Maquis she returned to Deep Space 9 to face punishment. She was sent to prison for her actions. (DS9: "For the Cause")
After her release in 2373, Yates and Sisko picked up where they had left off, with Sisko accepting her back to the station and into his life without a second thought. (DS9: "Rapture") Yates subsequently returned to work for the Bajorans.
In 2374, Yates agreed to act as convoy liaison officer aboard the Defiant while it served as escort for the PQ-1 convoy, as she knew many of the freighter captains involved with the mission. However, she complained that she had no idea the job would involve writing twenty log entries a day and filling out formal reports for Starfleet every night. She joked that the reason she didn't join Starfleet was because she couldn't do the paperwork. Yates was still present aboard the Defiant when it received a distress call from Captain Lisa Cusak, and she took part in shifts with the Defiant crew in keeping an open communication line to the stranded Captain. However, Sisko felt uncomfortable having Kasidy, a civilian, aboard the Defiant, and she was worried by his unfriendly behavior. He later apologized and promised to make it up to her over dinner. (DS9: "The Sound of Her Voice")
That year she was greeted at by Benjamin Sisko after she had docked her freighter on the upper pylon of Deep Space 9. She then explained that she was home because her next three cargo runs had been reassigned, blaming it on "bureaucrats", not knowing it was in fact Sisko who made the arrangements. (DS9: "Take Me Out to the Holosuite")
Later that year, Sisko proposed to Yates, and she accepted, causing much celebration among the Bajoran people, who began to plan a grand wedding for their Emissary of the Prophets. (DS9: "Penumbra") Sisko initially backed out of the marriage, having been warned by the Prophets that he and Kasidy could not walk the same path. Sisko decided to ignore the warning and the two were married by Admiral William Ross in a private ceremony on Deep Space 9. (DS9: "'Til Death Do Us Part")
The first few weeks of their marriage were not all clear sailing, however. Shortly after their wedding, Yates destroyed some of Sisko's home-grown bell peppers in a failed attempt to cheer him up by cooking for him. Sisko attempted to keep Yates and her freighter out of the escalating Dominion War by having the Bajoran Freight and Shipping Authority take her off the active list, much to her annoyance; he later relented. (DS9: "The Changing Face of Evil")
Later in 2375, Yates discovered that she and her husband were going to have a baby. The pregnancy was unplanned, and Sisko surmised that his last contraception injection must have expired without him returning to the infirmary for another. Yates worried that something might happen to the baby following the Prophets' earlier warning to Sisko that marrying Kasidy would bring him sorrow. Sisko reassured his wife that nothing would happen to their baby, giving her his word as the Emissary. (DS9: "The Dogs of War")
During a battle with the Pah-wraith-possessed Dukat in the Bajoran Fire Caves, Sisko sacrificed his life to defeat the evil Kosst Amojan and joined the Prophets in the Celestial Temple, leaving Yates and their unborn child behind. Sisko later appeared to Kasidy in a vision, and promised her that he would be back, "maybe (in) a year, maybe yesterday. But I will be back." (DS9: "What You Leave Behind")
- "Family Business" (Season Three)
- "The Way of the Warrior" (Season Four)
- "For the Cause"
- "Rapture" (Season Five)
- "Far Beyond the Stars" (Season Six)
- "The Sound of Her Voice"
- "Take Me Out to the Holosuite" (Season Seven)
- "Badda-Bing, Badda-Bang"
- "'Til Death Do Us Part"
- "Strange Bedfellows"
- "The Changing Face of Evil"
- "The Dogs of War"
- "What You Leave Behind"
Kasidy Yates was portrayed by Penny Johnson.
In the script of "Family Business", in which Kasidy Yates first appears, she is described as "an attractive Human woman in her mid-thirties. Kasidy is the captain of her own ship, an independent interstellar freighter, and she bears herself with the confidence befitting her position. She is, however, a civilian, which allows her to be a little more relaxed with her crew than if she were in Starfleet."
Penny Johnson said of Yates, "She's a woman who's very strong in her beliefs, she's good at what she does, she is a wonderful, extraordinary woman for Benjamin Sisko, she's loving, romantic, I think she's sexy, I think she's powerful, I think she's a wonderful role model, and her full arc is from seeing her just as a person to a woman to a blossoming lover, and then to a real friend for life." (Hidden File 05, DS9 Season 7 DVD, Special Features)
Kasidy's middle name is given as Shameeka in the Star Trek Encyclopedia and in Star Trek: Celebrations. The name was used in an early draft of DS9: "'Til Death Do Us Part". Avery Brooks commented: "When Kasidy and Sisko were married they chose this middle name for Kasidy which looked like a character that the comedian Martin Lawrence would have invented. I said 'Wait a minute! Why did you pick that name? They went on to tell me that it had some deep African origin. And that a friend researched it etc. etc. until they remembered who they were talking to. That is to say that among other things I was born brown of African descent. But more importantly that I had studied. So I know what I am talking about". 
While the opening credits after the wedding continue to use just "Kasidy Yates", the scripts for those episodes use "Kasidy Yates-Sisko", and she is referred to in dialogue as "Mrs. Sisko".
By the time of Avatar, Yates has built a home on Bajor based on Sisko's plans. In Unity, Yates gives birth to a daughter (who is named Rebecca Jae Sisko) and is reunited with Benjamin Sisko. In Raise the Dawn, Kasidy and Rebecca go to live with Sisko on the USS Robinson.
The novel Articles of the Federation gives her youngest brother's name as Kornelius.
In the short story "The Dreamer and the Dream", her baby is a boy named Jonathan.