Tsar Alexander I was twenty eight in 1805. Upon his ascension to the throne four years previously he had surrounded himself with a group of young noblemen, dismissing the old ministers who had served his father Paul I and appointing instead a Private Committee of his friends.
Count Nikolai Nikolaevich Novosiltsev (1761–1836) was responsible for drafting a constitution for Russia, which Alexander I adopted as part of the reforms he undertook (then went on to ignore) at the beginning of his reign. Like Czartoryski, Novosiltsev was an important part of the negotiations that established the Allies against Napoleon. He later served in Poland, heading the Russian secret police there (the okhrana, ancestors of today's FSB.)
Prince Pyotr Mikhailovich Volkonsky (1776-1852) was a part of the plot to assassinate Alexander's father Tsar Paul I. After Alexander I's ascension, he became a close advisor, commanding the Russian troops at the Battle of Austerlitz. The Volkonskys were a famous noble family descended from the Rurik dynasty who ruled ancient Kievan Rus, the ancestor of Imperial Russia. Tolstoy was related to the family through his mother; his fictional Bolkonskys are a thinly disguised version of his mother's family.
Count Pavel Alexandrovich Stroganov (1774-1817) was a Russian diplomat, military commander and member of Alexander I's Privy Council. It is possible that he is the Stroganov who lent his name to the famous Russian dish beef stroganov (or stroganoff; sautéed beef with mushrooms and sour cream). See here for a recipe.