Philander Chase Knox (May 6, 1853–October 12, 1921) was an American lawyer and politician who served as Attorney General and U.S. Senator and was Secretary of State from 1909-1913.
Knox was born in Brownsville, Pennsylvania and graduated from Mount Union College in 1872. He was admitted to the bar in 1875 and practiced in Pittsburgh, Pennsylvania. From 1876-1877 he was Assistant United States Attorney for the Western District of Pennsylvania and became President of the Pennsylvania Bar Association in 1897.
As counsel for the Carnegie Steel Company , he took a prominent part in organizing the United States Steel Corporation in 1901. He served as Attorney General in the cabinets of Presidents McKinley and Theodore Roosevelt from 1901 to 1904. In June 1904, when he was appointed by Governor Samuel W. Pennypacker of Pennsylvania to fill the unexpired term of Matthew S. Quay in the United States Senate; in 1905 he was re-elected to the Senate for the full term (to 1909). After an unsuccessful bid for the Republican Presidential nomination in 1908, he served as Secretary of State in President Taft's cabinet from March 6, 1909 until March 5, 1913.
As Secretary of State, Knox reorganized the Department on a divisional basis, extended the merit system to the Diplomatic Service up to the grade of chief of mission, pursued a policy of encouraging and protecting American investments abroad, and accomplished the settlement of the Bering Sea controversy and the North Atlantic fisheries controversy.
Following his term of office, he resumed the practice of law in Pittsburgh. He was again elected to the Senate from Pennsylvania and served from 1917 to 1921. Knox died in Washington, D.C. in 1921.
|- style="text-align: center;"
| width="30%" |Preceded by:
Matthew S. Quay
| width="40%" style="text-align: center;" |U.S. Senator from Pennsylvania
1904–1909
| width="30%" |Succeeded by:
George T. Oliver
|- style="text-align: center;"
| width="30%" |Preceded by:
Robert Bacon
| width="40%" style="text-align: center;" |United States Secretary of State
1909–1913
| width="30%" |Succeeded by:
William Jennings Bryan
|- style="text-align: center;"
| width="30%" |Preceded by:
George T. Oliver
| width="40%" style="text-align: center;" |U.S. Senator from Pennsylvania
1917–1921
| width="30%" |Succeeded by:
William E. Crow
