Charles Robert Cross (March 29, 1848 – November 16, 1921) was an American physicist and chair of the physics department at the Massachusetts Institute of Technology from 1877 to 1917.

When he was 14, his family moved to Newburyport, Massachusetts where he attended the Putnam Free School, graduating in 1865.

Cross became chair of the MIT physics department in 1877, after the resignation of Edward Pickering.

In addition, Cross was President of the Appalachian Mountain Club in 1880 and the Chairman of the Rumford Committee of the American Academy of Arts and Sciences from 1897 to 1921.

Cross died November 16, 1921, at his Pill Hill home in Brookline, Massachusetts.