1. Tsarevitsj Nicolaas Aleksandrovitsj
Tsarevich Nicholas Alexandrovich was the eldest son of Russian Emperor Alexander II and was supposed to become the next tsar. He was born on September 20, 1843. Sadly, he died from meningitis on April 24, 1865, at the age of 21. After his death, his younger brother Alexander became Tsar Alexander III.