Orazio Mariani (21 January 1915 – 16 October 1981) was an Italian athlete who competed mainly in the 100 metre sprint and competed at the 1936 Summer Olympics.
Mariani competed for Italy in the 1936 Olympic Games, held in Berlin, Germany, in the 4 x 100 metre relay, where he won the silver medal with his team mates Gianni Caldana, Elio Ragni and Tullio Gonnelli.
Mariani finished second behind Tinus Osendarp in the 100 yards event at the British 1938 AAA Championships. Soon after, in September at the 1938 European Athletics Championships, Mariani won the silver medal in the 200 metres.
Orazio Mariani has won 8 times the individual national championship.