Nathan Clifford (June 17, 1867 – November 6, 1919) was an American lawyer, businessman and politician from Portland, Maine.

Clifford, a Democrat, served as Mayor of Portland from 1906 to 1907[1] after defeating incumbent James Phinney Baxter.

He was the only Democrat to hold that office from Luther Moore in 1854 and Carlton Day Reed Jr. in 1964.

His grandfather, who was also named Nathan Clifford, was an Associate Justice of the Supreme Court of the United States from 1858 to 1881.

His father, William Henry Clifford, was a successful attorney.