Grand Duke Konstantin Pavlovich of Russia

Konstantin Pavlovich (Russian: Константи́н Па́влович; 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. For 25 days after the death of Alexander I, from 19 November (O.S.)/1 December 1825 to 14 December (O.S.)/26 December 1825 he was known as His Imperial Majesty Konstantin I Emperor and Sovereign of Russia, although he never reigned and never acceded to the throne. His younger brother Nicholas became tsar in 1825. The succession controversy became the pretext of the Decembrist revolt.

Konstantin was known to eschew court etiquette and to take frequent stands against the wishes of his brother Alexander I, for which he is remembered fondly in Russia, but in his capacity as the governor of Poland he is remembered as a hated ruler.