Frank Douglas-Pennant, 5th Baron Penrhyn (21 November 1865 – 3 February 1967) was a British nobleman and Justice of the Peace for Northamptonshire.
He attended Eton College and the RMC, Sandhurst and became an officer in the King's Royal Rifle Corps (KRRC), fighting in the Boer War.
Early in the First World War he was made Lieutenant Colonel of the KRRC's 10th (Service) Battalion.
In 1949 the 4th Baron Penrhyn died without issue, leaving the direct male line from the 1st Baron extinct.
Frank Douglas-Pennant thus succeeded to the barony at age 83.