| Schull & Skibbereen Light Railway 4 | |
| Powertype: | Steam |
| Builder: | Nasmyth, Wilson & Co. |
| Serialnumber: | 341 or 342 |
| Builddate: | 1888 |
| Uicclass: | 2′B n2t |
| Leadingdiameter: | 1feet |
| Driverdiameter: | 3feet |
| Axleload: | 9LT |
| Weightondrivers: | 18LT |
| Locoweight: | 24LT |
| Fueltype: | Coal |
| Fuelcap: | 0LT |
| Watercap: | 500impgal600impgal |
| Boilerpressure: | 1502NaN2 |
| Firearea: | 9square feet |
| Tubearea: | 453square feet |
| Fireboxarea: | 56square feet |
| Cylindercount: | Two |
| Cylindersize: | 12x |
| Tractiveeffort: | 82602NaN2 |
| Operator: | SSLR » Great Southern Railways » CIÉ |
| Operatorclass: | GSR/CIÉ: 4S or DN5 |
| Numinclass: | 1 |
| Fleetnumbers: | 4 |
| Officialname: | Erin |
| Withdrawndate: | 1954 |
Schull and Skibbereen Railway 4 Erin was a locomotive manufactured by Nasmyth, Wilson and Company of Patricroft near Manchester in 1888. It was the Schull and Skibbereen Railway's fourth locomotive.
In 1925, the railway was absorbed into the Great Southern Railways and renumbered 4, and placed in Class 4 or Class DN5 as the sole member. Following the GSR classification by wheel arrangement, "D" meaning a locomotive with a arrangement, "N" meaning Narrow Gauge. The wheel arrangement is unusual for tank locomotives but more common on narrow gauge than standard.
The locomotive was withdrawn and scrapped in 1954.