| Guillermo Calegari Sr. | |
| Full Name: | Guillermo Julio Calegari |
| Sport: | Sailing |
| Birth Date: | 13 September 1924 |
| Birth Place: | Buenos Aires, Argentina |
| Death Place: | Buenos Aires, Argentina |
Guillermo Julio Calegari Sr. (13 September 1924 – 21 July 2023) was an Argentine sailor. He competed in the Star event at the 1972 Summer Olympics.[1]