Ensign Marian A. McAllum was a Starfleet officer during the Dominion War.
In 2374, a file from the USS Akagi reported McAllum missing in action. A file from the USS Zapata reported her killed. (DS9: "In the Pale Moonlight")
This character was only mentioned in writing.
McAllum's name appeared on the casualty list
display seen on a computer readout in that episode. It is unclear if the Zapata was her home station.