Alexis of Russia
Tsarevich Alexei Alexeyevich (, "Aleksey Alekseyevich"; 15 February 1654 – 17 January 1670) was the second son and heir of Tsar Alexis of Russia and Maria Miloslavskaya, brother of Tsar Feodor III, Tsar Ivan V, and Tsarevna Sophia and half-brother of Tsar Peter the Great.