Grau (; ) is a common surname used in Catalan and German, meaning respectively "grade", coming from the Latin word gradus, or "gray". Notable people with the surname include:
Agustí Grau (1893–1964), Spanish (Catalan) composer Albin Grau (1884–1971), German artist, architect and occultist Alexander Grau (born 1973), German racing driver Benjamin Grau (born 1945), Spanish (Catalan) former motorcycle racer Dieter Grau (1913–2014), German rocket scientist Doris Grau (1924–1995), American actress, script supervisor and voice actress Emili Prats Grau (born 1946) Andorran politician Emilio Grau Sala (1911–1975), Spanish (Catalan) artist Enrique Grau (1920–2004), Colombian artist Eulàlia Grau (born 1946), Spanish (Catalan) artist Francisco Grau (1947–2019), Spanish musician Fritz Grau (1894–?), German athlete Hugo Grau (1899–1984), German biologist Jacinto Grau (1877–1958), Spanish playwright Jaume Grau (born 1997), Spanish footballer Jeff Grau (born 1979), American former football player Joan Carretero i Grau (born 1955), Spanish (Catalan) politician Jorge Grau (1930–2018), Spanish (Catalan) director, scriptwriter, playwright and painter José Sanchis Grau (1932–2011), Spanish comic book writer Lester W. Grau (), American military writer Lorenzo Batlle y Grau (1810–1887), President of Uruguay from 1868 to 1872 Martin Grau (born 1992), German steeplechase runner Maurice Grau (1849–1907), Austrian-born American impresario Miguel Grau Seminario (1834–1879), Peruvian naval officer Nicolás Grau (born 1983), Chilean business manager, economist and politician Olga Grau (born 1945), Chilean writer, professor, philosopher Oliver Grau (born 1965), German art historian Polita Grau (1915–2000), former First Lady of Cuba Ramón Grau (1881–1969), President of Cuba 1933–34 and 1944–48 Raúl Cubas Grau (born 1943), President of Paraguay, 1998–1999 Roberto Grau (1900–1944), Argentine chess player Roberto Diego Grau (born 1970), Argentine rugby player Santiago Grau (born 1963), Spanish (Catalan) field hockey player Shirley Ann Grau (1929–2020), American writer Vicente Grau Juan (born 1968), Spanish athlete