Paul I of Russia
Paul I (; "Pavel Petrovich") ( – ) reigned as Emperor of Russia between 1796 and 1801. Officially, he was the only son of Peter III and Catherine the Great, though Catherine hinted that he was fathered by her lover Sergei Saltykov, who also had Romanov blood, being a descendant of the first Romanov tsar's sister, Tatiana Feodorovna Romanova.
Peter Ludwig von der Pahlen
He extracted from the emperor the written order to arrest his son and heir, Alexander Pavlovich, and showed this to him in order to overcome his fluctuation in the plot. He was present during Paul's strangling on the night of March 12, 1801. After the assassination he acquired an irreconcilable enemy in the Empress Maria Feodorovna who prevented him from occupying any important post under Alexander's reign. On 1 April 1801, he was discharged from the service and ordered to withdraw into his estates in Courland. Pahlen died in Mitava on February 13, 1826.