The Córas Iompair Éireann 421 Class was a railway locomotive, built by the CIÉ at Inchicore Works between 1962–1963 and designed for branch line traffic use and shunting. The 421 Class was a larger development of the earlier 401 Class, and were fitted with a Maybach MD220 engine of 420 horsepower (310 kW) with diesel hydraulic transmission via a Mekydro KL64U transmission. Unlike the earlier E401 class, these locomotives were fitted for multiple operation. They were of C wheel arrangement. Three of these locomotives have been preserved, as follows: