Helmut Heinrich Schaefer (February 14, 1925 in Großenhain, Weimar Republic – December 16, 2005 in Tübingen, Germany) was a German mathematician, who worked primarily in functional analysis.

His two best known scientific monographs are titled Topological Vector Spaces (1966) and Banach Lattices and Positive Operators (1974).

(Roquette & Wolff, 2006) As teenager, Helmut Schaefer attended the Sankt Afra boarding school for gifted children in Meissen, Germany on a merit-based scholarship.

He remained active in mathematical research until the year 1999, at which point he completely dedicated himself to his lifelong hobby of astronomy, especially astrophotography.

Over the years, he was able to attract many students to functional analysis, combining an expectation of high achievement with a tolerant, humorous, and factual attitude.