"Bulldog nose" is the nickname given, due to their appearance, to several diesel locomotives manufactured by GM-EMD and its licensees from 1939 to 1970. The term originated with EMD F-units, as well as later E-unit models such as the E7, E8, and E9. The bulldog nose design, which has been described as "iconic" consists of two narrow front cab windows, swept back above a protruding nose section, usually with a prominent nose-top mounted headlight. This bore resemblance to a dog's face. It was a blunter and more vertical variation of the similar "slant nose" style, which featured a more sloped front and often less protruding headlight. Examples of this included the EMC E1.

The style was highly influential in locomotive design internationally during the same period, with many diesel and elecrtric locomotives in Europe and Australia among other places adopting similar styling during the 1940s, 50s and 60s.