The UM12C is a type of diesel-electric locomotive manufactured by GE for Southeast Asian rail operators.

The Manila Railroad Company (MRR) announced the dieselization of its locomotive fleet in 1954.

The agency bought fifty units in which thirty were streamlined mainline locomotives and twenty were switchers.

Along with the cab unit 1000 class, they formed the mainline locomotive fleet in Luzon until the late 1970s and the early 1980s.

Starting in 1973, a newer GE Universal Series type numbered the PNR 900 class was introduced on mainline passenger services.