Hermann Friedrich Lossen (7 November 1842 – 27 August 1909) was a German surgeon born in Emmershäuser Hütte, Hesse.

He studied under Carl von Voit (Munich), Friedrich Daniel von Recklinghausen (Würzburg), Bernhard von Langenbeck (Berlin) and Theodor Billroth (Vienna), earning his medical doctorate in 1866 from the University of Würzburg.

In 1866 he became habilitated for surgery at Heidelberg, where in 1874 he was appointed associate professor.

Lossen was author of a revision of Carl Hueter's Grundriss der Chirurgie (Outline of surgery), which was subsequently published over several editions (7th edition issued as Lehrbuch der allgemeinen und speciellen Chirurgie).

[1] Other noted works by Lossen include: This article about a German person in the field of medicine is a stub.