Orville Hitchcock Platt (July 19, 1827 – April 21, 1905) was a United States senator from Connecticut.

Platt was a prominent conservative Republican and by the 1890s he became one of the "big four" key Republicans who largely controlled the major decisions of the Senate, along with William B. Allison of Iowa, John Coit Spooner of Wisconsin and Nelson W. Aldrich of Rhode Island.

He later had a son, named James Perry Platt, who became Judge of the United States District Court.

[7] In the U.S. Senate, Platt presided over the impeachment trial of Judge Charles Swayne, which was held in late 1904 and early 1905.

[7] Platt died on April 21, 1905, aged 77, at his summer home, "Kirby Corners", in Washington, CT, and was interred in the Cemetery on the Green in the same town.