Luis Roberto (Ruben) Piazzini (11 May 1905 - 4 March 1980) was an Argentine chess master.
He participated many times in Argentine championships, and was an Argentine Champion in 1933 winning ARG-ch Torneo Mayor and a match for the title against Jacobo Bolbochán (5.5 : 2.5). In 1934/35, he lost a match to Roberto Grau (5.5 : 7.5), lost a match to Carlos Guimard (2.5 : 7.5) in 1938, and lost a match to Carlos Maderna (6 : 8) in 1940.
In 1934, he tied for 7-8th in Mar del Plata International Chess Tournament (Aaron Schwartzman won). In 1934/35, he won South American Chess Championship in Buenos Aires. In 1936, he tied for 9-10th in Mar del Plata (it, Isaias Pleci won). In 1944, he took 4th in Buenos Aires (La Regence). In 1952, he won the Club Argentino de Ajedrez Championship in Buenos Aires. In 1959, he took 8th in Quilmes (Alberto Foguelman won).
Piazzini played twice for Argentina in Chess Olympiads: