The first wife of Benjamin Sisko and mother of Jake, killed aboard the USS Saratoga at the Battle of Wolf 359.
Jennifer Sisko was a civilian who met Benjamin Sisko on a beach on Earth while he was a young Starfleet officer. They married and had a son, Jake, and she travelled with her husband on his postings, including aboard the USS Saratoga, where he served as first officer.
When the Borg attacked the Federation fleet at Wolf 359, the Saratoga was destroyed and Jennifer was killed. Sisko was forced to leave her body behind in the wreckage as he rescued their son. Her loss haunted him for years, and when he encountered the Prophets inside the Bajoran wormhole they used her image to communicate with him and to help him confront his grief.
A mirror universe version of Jennifer, a scientist allied with the Terran rebellion, later drew Sisko into that universe's conflicts. Jennifer's death defined Sisko's state of mind when he arrived at Deep Space Nine, and his healing from it is one of the series' earliest arcs.