Nicolai is a Frisian (northern part of The Netherlands) surname , and may refer to:
In music Philipp Nicolai (1556–1608), German Lutheran pastor, poet, and composer Carl Otto Ehrenfried Nicolai (1810 – 1849) German composer, conductor, and founder of the Vienna Philharmonic Bruno Nicolai (1926–1991), Italian film music composer, orchestra director, and musical editor Carsten Nicolai (aka Alva Noto; born 1965), German sound artist
In literature Christoph Friedrich Nicolai (1733–1811), German writer and bookseller
In other fields Anton Nicolai (died 1474), Polish Roman Catholic bishop Dorothea Nicolai (born 1962), German costume designer, stage designer Ernst Anton Nicolai (1722–1802), German physician and chemist Ernst August Nicolai (1800–1875), German physician and naturalist Friedrich Bernhard Gottfried Nicolai (1793–1846), German astronomer Hermann Nicolai (born 1952), German theoretical physicist Norica Nicolai (born 1958), Romanian lawyer and politician Ruben Nicolai (born 1975), Dutch television presenter and comedian William S. Nicolai (born ?), U.S. inventor and entrepreneur
See also Luigi Nicolais (1942–2026), Italian politician and academic