Johann August of Saxe-Gotha-Altenburg
, 17 February 1704
- d. Stadtroda
, 8 May 1767
), was a German prince, member of the House of Saxe-Gotha-Altenburg.
He was the fifth but second surviving son of Frederick II, Duke of Saxe-Gotha-Altenburg and Magdalene Augusta of Anhalt-Zerbst.
In Stadtroda on 6 January 1752 Johann August married Luise Reuss of Schleiz, the widow of his younger brother, Christian Wilhelm. They had four children:
- Auguste Luise Fredericka (b. Stadtroda, 30 November 1752 - d. Rudolstadt, 28 May 1805), married on 28 November 1780 to Frederick Karl I of Schwarzburg-Rudolstadt.
- stillborn son (Stadtroda, 11 November 1753).
- stillborn son (Stadtroda, 27 December 1754).
- Luise (b. Stadtroda, 9 March 1756 - d. Ludwigslust, 1 January 1808), married on 1 June 1775 to Frederick Franz I, Grand Duke of Mecklenburg-Schwerin. She was a direct ancestor of the Queen Victoria of the United Kingdom, and, by her, of the actual British Royal Family.