Sergeant Hartmann is a minor villain appearing in both the novel and film Where Eagles Dare.
Hartmann was an SS guard stationed in the Schloss Adler. He was summoned to the Golden Hall by his superior, Paul Kramer, to keep a watch on the seated Olaf Christiansen, Lee Thomas and Edward Carraciola, who Johann Schmidt claimed were imposters. But truth, Schmidt was the imposter. He was actually undercover British spy John Smith. An enraged Kramer yelled for Hartmann to attack Smith, but the Welshman acted quicker, knocking the Nazi sergeant unconscious with one punch. Afterward, the knocked out Hartmann was injected with a sleeping drug which kept him and the other Nazis in the Golden Hall sound asleep for the remainder of the Allies' mission. Hartmann's fate after this is unknown.
In the film, Hartmann does not survive. He stands menacingly in the background during the meeting with a slung MP40 at the ready. When Colonel Kramer yells for him to kill John Smith, he moves to shoot Smith, but, instead of knocking him out, Smith shoots Hartmann with a silenced Walther PPK, killing him.