| Type: | Bishop |
| Guglielmo Aretini-Sillani | |
| Bishop of Terracina, Priverno e Sezze | |
| Church: | Roman Catholic Church |
| Diocese: | Terracina, Priverno e Sezze |
| Term Start: | 6 April 1835 |
| Term End: | 4 December 1853 |
| Retired: | --> |
| Predecessor: | Bernardino Panzacchi |
| Successor: | Nicola Bedini |
| Ordination: | 12 June 1813 |
| Consecration: | 26 April 1835 |
| Consecrated By: | Pietro Francesco Galleffi |
| Birth Date: | 18 August 1786 |
| Birth Place: | Sigillo, Papal States |
Guglielmo Aretini-Sillani (18 August 1786 – 12 August 1875) was an Italian Roman Catholic bishop.
Ordained to the priesthood on 12 June 1813, Aretini-Sillani was named bishop of the Roman Catholic Diocese of Terracina, Priverno e Sezze, Italy in April 1835 and resigned on 4 December 1853.[1]