Larson Giovanni Diaz Martinez (born 23 March 1994 in Santa Rosa, Misiones Department, Paraguay) is a Paraguayan javelin thrower.
He has a scholarship with the Secretaria Nacional de Deportes and represents Paraguay Marathon Club in the Federación Paraguaya de Atletismo.
Díaz claimed a silver medal at the 2013 South American Junior Championships in Athletics.
Larson Giovanni Diaz Martinez and María Caballero were the best athletes of the 2015 Paraguayan Athletics Championships.He belongs to a line of Paraguayan throwers, such as Ramón Jiménez Gaona (discus), Víctor Fatecha (javelin), Nery Kennedy (javelin) and Edgar Baumann (javelin), who all had successful careers.