| Prince John August | |
| Spouse: | Countess Louise Reuss of Schleiz |
| Issue: | Augusta, Princess of Schwarzburg-Rudolstadt Louise, Duchess of Mecklenburg-Schwerin |
| House: | House of Saxe-Gotha-Altenburg |
| Father: | Frederick II, Duke of Saxe-Gotha-Altenburg |
| Mother: | Magdalene Augusta of Anhalt-Zerbst |
| Birth Date: | 17 February 1704 |
| Birth Place: | Gotha |
| Death Place: | Stadtroda |
Johann August of Saxe-Gotha-Altenburg (17 February 1704 – 8 May 1767), was a German prince, member of the House of Saxe-Gotha-Altenburg.
He was born in Gotha, the fifth but second surviving son of Frederick II, Duke of Saxe-Gotha-Altenburg and Magdalene Augusta of Anhalt-Zerbst.
In 1725 he entered in the Imperial army and fought in Italy and Hungary. In the Battle of Grocka he was wounded and then spent some time in Altenburg to recover. Later he resumed his military duties and fought in the War of the Austrian Succession in Silesia, Bohemia, Bavaria and the Rhine. He eventually became Imperial Field Marshal and received his own dragoon regiment.
He lived with his family in Stadtroda, where shortly before his death he received a visit from King Frederick the Great of Prussia. He was awarded the Polish Order of the White Eagle.
On 6 January 1752 at Roda (Stadtroda after 1925), Johann August married Louise Reuss of Schleiz, co-Countess of Limpurg-Gaildorf since 1734 [as her mother's only surviving child][1] (Staffelstein, 3 July 1726 – Stadtroda, 28 May 1773), widow of his younger brother Christian Wilhelm. They had four children: