| Unit Pref: | Imperial |
| Settlement Type: | Township |
| Official Name: | Erin Township |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | Stephenson |
| Leader Title: | Supervisor |
| Leader Name: | Brian Diddens |
| Area Total Sq Mi: | 18.15 |
| Area Land Sq Mi: | 18.15 |
| Area Water Sq Mi: | 0 |
| Area Water Percent: | 0 |
| Population As Of: | 2010 |
| Population Density Sq Mi: | 22.6 |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Coordinates: | 42.3331°N -89.7769°W |
| Elevation Ft: | 1017 |
| Pop Est As Of: | 2016 |
| Pop Est Footnotes: | [1] |
| Population Est: | 396 |
| Blank Name: | FIPS code |
| Blank Info: | 17-177-24413 |
Erin Township is located in Stephenson County, Illinois. As of the 2010 census, its population was 410 and it contained 177 housing units.[2] The unincorporated community of Eleroy is located in the township.
Erin is Township 27 North, Range 6 (part) East of the Fourth Principal Meridian.
According to the 2010 census, the township has a total area of, all land.[2]
The Stage Inn (Section 14) was built along the Old State Road number 2, now U.S. Route 20, ½ mile east of Eleroy. The stone inn was a stop for the Frink, Walker & Company stage line that operated from Chicago to Galena 1839–1854. A stone barn across the road from the inn was demolished.[3]