Simon August, Count of Lippe (12 June 1727 – 1 May 1782), ruled the Principality of Lippe-Detmold from 1734 until 1782.

He was born in Detmold, the son of Simon Henry Adolph and Johanna Wilhelmine of Nassau-Idstein.

Under the influence of the Enlightenment, he issued a fiscal and social legislation and in 1749 he introduced, together with Adolf von Hillensberg, a budget in Lippe, so as to not spend money when no revenues were available.

They had a son: In Dessau on 9 November 1769 Simon August married thirdly princess Casimire of Anhalt-Dessau (Dessau, 19 January 1749 – Detmold, 8 November 1778), sister of his previous wife.

They had a son: In Braunfels Castle on 26 March 1780 Simon August married fourthly princess Christine of Solms-Braunfels (Braunfels, 30 August 1744 – Detmold, 16 December 1823).