Hanfried Lenz (22 April 1916 in Munich – 1 June 2013 in Berlin) was a German mathematician, who is mainly known for his work in geometry and combinatorics.

In 1939 when World War II broke out in Europe, he became a soldier in the western front and during a vacation he passed the exams for his teacher certification.

He was also politically active and in connection with his opposition to the rebuilding of the German army in the early 50s, he became a member of the Social Democratic Party (SPD) in 1954.

Later, partially due to being alienated by the student movement of the '60s, his leanings became more conservative again and in 1972 he left the SPD to join the Christian Democratic Union.

During his later years he also worked in the area of combinatorics and published a book on design theory (together with Dieter Jungnickel and Thomas Beth).