Roberto Gabriel Grau (18 March 1900 – 12 April 1944) was an Argentinian chess master. He was born and died in Buenos Aires. Grau played in many Argentinian championships. In 1921/22, he tied for 3rd–4th (ARG-ch 1 Mayor; Damian Reca won). In 1922, he tied for 2nd–3rd (ARG-ch 2; Benito Villegas won). In 1923/24, he tied for 2nd–4th (ARG-ch 3; Reca won). In 1924, he took 2nd, behind Richard Réti (ARG-ch 4). Grau played for Argentina in Chess Olympiads. He was one of the original signatories in the formation of FIDE at Paris 1924 (1st unofficial Chess Olympiad).