Charles Phelps "Charlie" Smyth was an American chemist. He was educated at Princeton University and Harvard University. From 1920 to 1963 he was a faculty member in the Princeton Department of Chemistry, and from 1963 to 1970 he was a consultant to the Office of Naval Research. He was awarded the Nichols Medal by the New York Section of the American Chemical Society in 1954.

Charles Henry Smyth Jr. was an American geologist. Born to a prominent family in Upstate New York, he studied geology at Columbia University before becoming a professor of geology at Hamilton College and Princeton University. At Princeton he strengthened the Department of Geology's graduate program.