Karel Pergler, known also by Anglicized Charles Pergler (Liblín, March 6, 1882 – Washington, D.C., August 14, 1954) was a Czech-American lawyer, journalist, diplomat and politician. He was a Czechoslovak First Republic ambassador to the United States and Japan. He served as the secretary of Professor Thomas Garrigue Masaryk from May 1918 in America.