Eta Valer Hentz (1895–1986) was a Hungarian-American fashion designer active in the US from the 1920s to the 1940s. Mainly known as Madame Eta, she was particularly known for flattering ready-to-wear clothing inspired by Ancient Greece and the Middle Ages.

Born in Budapest, Hentz studied at the Hungarian Royal State Academy of Industrial Arts.^[1] In 1923 she launched her career in New York, when she joined the high-end ready-to-wear wholesaler Maurice Rentner. Their label Ren-Eta, ran until the late 1940s.^[2] In the late 1930s, Hentz and Ann Sadowsky launched their own company, for which Hentz produced her best-known work.^[1] She was particularly known for a 1943 collection which used ancient Greek classical themes,^[2] and other inspirations included Cape Cod and the Middle Ages for a Winter 1945 collection.^[1]

She worked in the ready-to-wear industry, creating clothes that were inventive, chic and refined, and flattering, especially for more mature women.^[1] Her work stood out from that of other American women designers for being more structured and decorative, more comparable to the work of American men designers.^[2] She was known as the "museum designer" due to her work regularly drawing influence and inspiration from historical sources and museum objects.^[2][3] She celebrated her 25th anniversary as a designer in July 1948, with an Autumn collection in shades of grey showing Victorian and Edwardian influences.^[4]

Hentz had an ongoing association with Stephens College. In 1957, as a "leader of the fashion industry" she helped found a costume library and reference collection at the college,^[3] and was part of the college's Fashion Advisory Board in 1967 along with Mary Brooks Picken, Adele Simpson, Vera Maxwell, Jo Copeland, Pauline Trigère, Sally Victor, and Helen Lee.^[5] In April 1970, she was part of the judging panel for the college's student fashion show.^[6]

She died in 1986. Her archives, covering the years 1933-1967 are held by the Fashion Institute of Technology, New York.^[7]