Union Pacific 844, also known as the "Living Legend", is a class "FEF-3" 4-8-4 "Northern" type steam locomotive owned and operated by the Union Pacific Railroad for its heritage fleet. Built in December 1944 by the American Locomotive Company (ALCO) of Schenectady, New York, No. 844 is one of four surviving FEF Series locomotives and the only one in operation.

The locomotive operated in revenue service until 1959. It was stored while awaiting scrapping, along with the rest of the UP steam locomotive fleet. In 1960, railroad leaders recognized the benefits of having a steam program and retained No. 844 for special activities, the kernel of what has become the Union Pacific's heritage fleet. Today, it is one of UP's oldest serving locomotives and the only steam locomotive owned by a North American Class I railroad that has never been retired.