The Córas Iompair Éireann 201 Class was a class of 34 diesel electric locomotives manufactured by Metropolitan-Vickers at their Dukinfield Works in Manchester. They were a smaller, lighter and less powerful version of the 001 Class and were originally intended for branch line passenger and freight duties. They were introduced in 1956 and, although their duties changed over the years, were in regular service on the Irish railway network until the mid-1980s. Six were sold to Northern Ireland Railways (NIR) in 1986.

The Córas Iompair Éireann 001 Class locomotive was manufactured by Metropolitan-Vickers at their Dukinfield Works in Manchester. The 001 Class locomotive was the backbone of mainline passenger and freight train services on the Irish railway network for forty years from 1955 until the mid-1990s when they were replaced by the new 201 Class.