| Sport: | Water polo |
| Birth Date: | 4 August 1938 |
| Birth Place: | Florence, Italy |
Gianni Lonzi (born August 4, 1938) is an Italian water polo player who competed in the 1960 Summer Olympics, in the 1964 Summer Olympics, and in the 1968 Summer Olympics.
In 1960 he was a member of the Italian water polo team which won the gold medal. He played five matches.
Four years later he finished fourth with the Italian team in the water polo competition at the Tokyo Games. He played six matches.
At the 1968 Games he was part of the Italian team which finished again fourth in the Olympic water polo tournament. He played all nine matches.
As a head coach, Lonzi led Italy men's national team to win an Olympic silver medal in 1976, becoming one of a few sportspeople who won Olympic medals in water polo as players and head coaches.[1]
He is married from 1968 with the Italian fencer Olympic Champion Antonella Ragno.