Reginald Aldworth Daly (March 18,1871 – September 19,1957) was a Canadian geologist. He was a professor at Harvard University from 1912 until 1942, after working as a field geologist for the Canadian International Boundary Commission.

He examined the rocks along a 400 miles stretch at the 49th parallel, which led him to formulate a theory of the origins of igneous rocks. He published his seminal work Igneous Rocks and Their Origin in 1914. He was awarded the Penrose Medal in 1935 and the William Bowie Medal in 1946.

Craters on Mars and the Moon are named in his honor.

1871 births | 1957 deaths | Canadian geologists | Penrose Medal winners