Prince John Konstantinovich of Russia (died 1918)

Prince John Konstantonovich of Russia, born as Grand Duke John Konstantinovich of Russia, sometimes also known as Prince Ivan, Prince Ioann or Prince Johan, was the eldest son of Grand Duke Konstantin Konstantinovich of Russia by his wife, Yelizaveta Mavrikievna, née Princess Elisabeth of Saxe-Altenburg. He was described by contemporaries as a gentle, religious person, nicknamed "Ioannchik" by his relatives.