Matías Díaz (born 16 March 1993 in Mendoza) is an Argentina rugby union player who plays mostly in the Tight head prop position. He currently plays with the New Zealand team Highlanders in Super Rugby. He was called up by Rodolfo Ambrosio into the Argentina under-20 side for the 2012 IRB Junior World Championship, and kept his position for the 2013 IRB Junior World Championship. He was initially named in Argentina's squad for the 2015 Rugby World Cup but then was immediately replaced by Juan Pablo Orlandi after getting injured.