Kathryn Janeway's fiance on Earth, who believed Voyager was lost and eventually married someone else.
Mark Johnson was engaged to Kathryn Janeway when Voyager left on its mission to the Badlands, and he cared for her dog while she was away. Stranded in the Delta Quadrant, Janeway often wondered whether he was waiting for her, and in Persistence of Vision a telepathic attack conjured an illusion of Mark to distract her.
When letters from home finally reached Voyager in Hunters, Janeway learned that Mark, believing the ship lost, had moved on and married another woman.