Heinz Otto Cordes (March 18, 1925 – October 30, 2018) was a German-American mathematician, specializing in partial differential equations (PDEs).

[1] He is known for the Aronszajn–Cordes uniqueness theorem for solutions of elliptic PDEs (due independently to Nachman Aronszajn).

This research led him to study Dirac operators with their connections with relativistic quantum mechanics.

He declined an invitation to address the International Congress of Mathematicians held in Moscow in 1966.

For the academic year 1971–1972, Cordes was a visiting professor at Lund University, where he gave a course on pseudodifferential operators via a C*-algebra approach.