Sir Percival Donald Leslie Fynn, CMG (16 August 1872 – 25 April 1940) was a Rhodesian politician.

He was Treasurer in the First Cabinet of Southern Rhodesia.

In 1933, he pledged his support to Godfrey Huggins for a government of national unity: this led to the merger of the Rhodesia Party and the Reform Party into the United Party. Under Higgins, he was Minister without Portfolio from 1934 until 1935 and Minister of Internal Affairs from 1935 until 1939.