Frank Cyril Tiarks OBE (also known as FC Tiarks) (July 9, 1874 - April 7, 1952) was a British banker.

Tiarks married Emmy Maria Franziska Brödermann of Hamburg, Germany, on November 18, 1899.

Among his appointments were a directorship of the Bank of England (1912-1945); a partnership in J. Henry Schröder and Co; a partnership in the Anglo-Iranian Oil Company (1917-1948); and High Sheriff of Kent (1927.

Tiarks was reputedly a member of the British Union of Fascists and an associate of Oswald Mosley. He was also a member of the Anglo-German Fellowship.