| Karl August | |
| Succession: | Prince of Waldeck and Pyrmont |
| Reign: | 1 January 1728 – 29 August 1763 |
| Predecessor: | Friedrich Anton Ulrich |
| Successor: | Friedrich Karl August |
| Spouse: | Countess Palatine Christiane Henriette of Zweibrücken-Birkenfeld |
| Issue: | Prince Charles Friedrich Karl August, Prince of Waldeck and Pyrmont Prince Christian George I, Prince of Waldeck and Pyrmont Princess Caroline Princess Louise Prince Louis |
| House: | House of Waldeck and Pyrmont |
| Father: | Friedrich Anton Ulrich, Prince of Waldeck and Pyrmont |
| Mother: | Countess Palatine Louise of Zweibrücken-Birkenfeld |
| Birth Date: | 24 September 1704 |
| Birth Place: | Hanau, Waldeck |
| Death Place: | Arolsen, Waldeck and Pyrmont |
Karl August Friedrich of Waldeck and Pyrmont (24 September 1704 – 29 August 1763) was Prince of Waldeck and Pyrmont and commander of the Dutch forces in the War of Austrian Succession.
Karl was the second son of Friedrich Anton Ulrich, Prince of Waldeck and Pyrmont and Countess Palatine Louise of Zweibrücken-Birkenfeld, youngest child of Christian II, Count Palatine of Zweibrücken-Birkenfeld. In 1728 his father and his elder brother Christian Philip died, and so he became Prince of Waldeck and Pyrmont.
The Waldecks had a tradition of military service in the Dutch Army. Prince Georg Friedrich of Waldeck had already led the Dutch army in the War of the Grand Alliance. In the War of Austrian Succession, Karl was appointed as commander of the Dutch Army by the States-General of the Netherlands, as counterbalance to William IV, Prince of Orange, who relied completely on his brother-in-law the Duke of Cumberland. The Dutch army under Waldeck's command was defeated in the Battle of Fontenoy, the Battle of Rocoux and the Battle of Lauffeld. In 1746, Karl became Fieldmarshal of the Holy Roman Empire.
In Zweibrücken, on 19 August 1741, Karl August married his first cousin Countess Palatine Christiane Henriette of Zweibrücken-Birkenfeld (1725–1816), daughter of Christian III, Count Palatine of Zweibrücken.
The couple had seven children: