Louis Adams Frothingham (July 13, 1871 – August 23, 1928) was a United States representative from Massachusetts.

Frothingham was elected a member of the Massachusetts House of Representatives, and served as Speaker from 1904 to 1905.

He was the Republican nominee in the 1905 Boston mayoral election after narrowly defeating former Judge Henry S. Dewey.

Frothingham served as a major in the United States Army during World War I.

Frothingham was elected as a Republican to the Sixty-seventh and to the three succeeding Congresses and served from March 4, 1921, until his death on board the yacht Winsome in North Haven, Maine on August 23, 1928.