Tretter is a German and Austrian surname. Notable people with the surname include: Christiane Tretter (born 1964), German mathematician Felix Tretter (born 1949), Austrian psychiatrist, psychologist and cyberneticisn Hannes Tretter (1951–2025), Austrian lawyer and human rights expert J. C. Tretter (born 1991), American football player Jean-Nickolaus Tretter (1946–2022), American activist and LGBT archivist