17th century

[Rodion Romanovich]

Actually he wasn't a son of Ivan the terrible, but just a leading boyar in Muscovy who took power by intrigue, the final step being to depose of an impostor pretending to be Ivan the terrible's son Dmitriy:
http://en.wikipedia.org/wiki/Vasili_IV_of_Russia

Edit: the son that was struck down was called Ivan. Ivan the terrible also had a son called Dmitriy who was an infant by the time Ivan the terrible died, and he also had a son called Feodor, who was said to be mentally retarded and historically ended up a puppet of his protector Boris Godunov until Boris Godunov eventually ended up Tsar. Dmitriy, who might not have been mentally retarded and probably was intended to succeed Feodor after Feodor's death, died at young age, it's suspected that Boris Godunov had something to do with it. Despite much opposition to his rule, and conspiracies of various kinds, Boris remained Tsar until dying from natural causes, being succeeded by his own son Feodor, who became Feodor II. Feodor II was however less lucky than his father and ended up murdered by the boyars within his first and only year as Tsar, and in the following chaos an impostor pretending to be Ivan the terrible's son Dmitriy became tsar (because there were rumors around that Dmitriy was still alive). It was this False Dmitriy that Vassili IV killed to become tsar. In 1608 another impostor pretending to be Dmitriy, False Dmitriy II, appeared, but wasn't able to gain the title of Tsar from Vasili IV. For good reason the period has been called complex...