Johann Nelböck, also Hans Nelböck (May 12, 1903, Brandel near Lichtenegg in Upper Austria–February 3, 1954, Vienna) was an Austrian former student of Moritz Schlick, who was the founder of the group of philosophers and scientists known as the Vienna Circle.

After attending the gymnasium in Wels Nelböck studied philosophy at the University of Vienna from 1925 on with Moritz Schlick, who was his doctoral advisor, and graduated as Dr.phil. on March 21, 1931, with the doctoral thesis "The Importance of Logic im Empirism and Positivsm".[1] Twice Nelböck was sent to an mental hospital with the diagnosis "schizoid personality disorder". He had threatened to kill Schlick.