| Heinrich XLII | |
| Full Name: | de|Heinrich |
| House: | House of Reuss Younger Line |
| Father: | Heinrich XII of Reuss-Schleiz |
| Mother: | Countess Christine of Erbach-Schönberg |
| Spouse: | Princess Caroline of Hohenlohe-Kirchberg |
| Issue: | Heinrich LXII, Prince Reuss Younger Line Heinrich LXVII, Prince Reuss Younger Line |
| Birth Date: | 27 February 1752 |
| Birth Place: | Löhma, Reuss |
| Death Place: | Schleiz, Reuss Younger Line |
Heinrich XLII (de|Heinrich XLII Fürst Reuß zu Schleiz und Gera; 27 February 1752 – 17 April 1818) was a German prince of the House of Reuss.
He succeeded as Count of Reuss-Schleiz on 25 June 1784, and also to Reuss-Gera on 26 April 1802, when the counties were united as Reuss-Schleiz und Gera. On 9 April 1806, the united county was raised to a principality.[1]