Gerrit Smith Miller Jr. (December 6, 1869 – February 24, 1956), was an American zoologist and botanist.

He graduated from Harvard University in 1894 and worked under Clinton Hart Merriam at the United States Department of Agriculture.

In 1906 he traveled to France, Spain, and Tangier on a collecting trip.

In 1915, he published results of his studies of casts of specimens associated with the Piltdown Man, concluding that the jaw actually came from a fossil ape and that the skullcap came from a modern human.

[1] Miller was elected to the American Academy of Arts and Sciences in 1921.