Lieutenant Commander Jon S. Monson was a Starfleet officer during the Dominion War.
In 2374, as well as later on in 2375, files from starships Akagi and Zapata reported Monson killed in action. (DS9: "In the Pale Moonlight", "What You Leave Behind")
This character was only mentioned in writing.
Monson's name appeared on the casualty list
display seen on a computer readout in that episode.