Nelson Horatio Darton (December 17, 1865 – February 28, 1948) was a geologist who worked for the United States Geological Survey.

He was born in Brooklyn, New York, started working in his uncle's drug business at thirteen years old, and becoming a practicing chemist.

He retired in 1936 at the age of 71 but was allowed to keep his office at the USGS, and he continued an active geological career with a focus on the geology of the Washington DC area.

He produced more than 200 publications and received many honors and awards.

Three weeks before he died in 1948, he was still coming daily to the USGS and gave a lecture to the Geological Society of Washington on the geology of the DC area.