| Official Name: | Duncan, Illinois |
| Settlement Type: | Unincorporated community |
| Pushpin Map: | Illinois#USA |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | Stark |
| Timezone: | Central (CST) |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Elevation Ft: | 659 |
| Coordinates: | 40.9836°N -89.7892°W |
| Area Code: | 309 |
| Blank Name: | GNIS feature ID |
| Blank Info: | 407481 |
Duncan is an unincorporated community in Stark County, Illinois, United States, located 4miles north-northwest of Princeville.
Duncan was laid out ca. 1870.[1] The community is named for James H. Duncan, a United States Congressman from Massachusetts from 1849 to 1853.[2]