Voyager casualty list

Seven of Nine reads Young's name in a list of deceased crewmembers

Charles Young was a Starfleet officer assigned to the starship USS Voyager, an ensign who was killed in the line of duty sometime before 2377. Young's name was read out on a casualty report of all who died during that starship's journey through the Delta Quadrant. (VOY: "Imperfection")

This character was only mentioned in writing.
This name was devised for the list; it was not mentioned as a casualty in any other episode. It is possible this name refers to one of the officers killed en route when Voyager was dragged to the Delta Quadrant.
As with many names on the "Imperfection" list, Charlie Young is an in-joke referring to the character on The West Wing.