Prince Ioann Konstantinovich of Russia
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Prince John Constantinovich of Russia (Russian: Иоанн Константиович) (5 July 1886 – 18 July 1918), also known as Prince Ioann, Prince Ivan or Prince Johan, was the eldest son of Grand Duke Constantine Constantinovich of Russia. He was described as a gentle, religious person. His relatives gave him the nickname of Ioannchick. He was born at Saint Petersburg, Russian Empire, and was in the House of Holstein-Gottorp-Romanov. He later married the Princess Helen of Serbia.