U.S. Marshal Marshall Mann. That's right, you read it right...Marshal Marshall.
Marshall is the long time partner of Mary Shannon, and probably the only one who really accepts her for the person she truly is, and in turn he's the only one she really, truly trusts. Marshall is a 5th generation Deputy U.S. Marshal. And because of it, he takes his job very seriously, but don't mistaken that seriousness as him being some stick in the mud...he's far from it.
Marshall is a walking, talking, and breathing encyclopedia of facts and usless trivia. And it's something that he's irritated Mary with on more then one occassion. Even though she may be hard pressed to say it, Mary wouldn't have him any other way.
Marshall is protective of the people he cares about, but none more then Mary. Marshall loves Mary, but came to a realization that they can't be together. And after that he soon got involved with police detective, Abigail. Marshall had asked for Mary's blessing to be with Abigail, and she gave it to him. As close as he is to Mary, does that mean he never gets mad at her? No, it doesn't. When he found out she told her ex, Raph, what she truly does he got pretty upset with her. Which was probably the most upset we've ever seen him at her. He justifiably felt she didn't have any right to tell Raph because her telling Raph also affected him. But he soon got over it...after having her engagement ring stuck on his finger all day long.
When the show ended, Marshall was not only engaged to Abigail, but he had also replaced Stan as being the boss of the ABQ WITSEC division.
FAMILY AND LOVE INTERESTS
Seth Mann -- Father
Abigail Chaffee -- Fiance' when the show ended