Grand Duke Konstantin Pavlovich of Russia
Konstantin Pavlovich (8 May [O.S. 27 April] 1779 – 27 June [O.S. 15 June] 1831) was a grand duke of Russia and the second son of Emperor Paul I and Sophie Dorothea of Württemberg. He was the heir-presumptive for most of his elder brother Alexander I's reign, but had secretly renounced his claim to the throne in 1823. Wikipedia