Hans Otto Friedrich Schlossberger (born 22 September 1887 in Alpirsbach, died 27 January 1960 in Stuttgart) was a German physician, who was known for his research in immunology, medical microbiology, epidemiology and antimicrobial chemotherapy, especially on syphilis, typhus, gas gangrene, diphtheria, erysipeloid of Rosenbach, tuberculosis, malaria and leptospirosis.

He was one of the leading immunologists and bacteriologists of Germany during his lifetime, and was a student and collaborator of the Nobel laureates Paul Ehrlich and Emil von Behring, two of the principal founders of the field of immunology.

He edited the journal Medical Microbiology and Immunology and the influential book Experimental Bacteriology.

He worked as an intern for the Nobel laureate Paul Ehrlich at the Royal Institute for Experimental Therapy while preparing his dissertation from 1912.

After working at the German Hospital in London, he was employed as scientific assistant of the Nobel laureate Emil von Behring at the University of Marburg Center of Hygiene.