Czar Nicolas I (ruled 1826-1855), assassinated 1855
Czar Alexander II (ruled 1855-1881), assassination attempts in 1866, 1879 (twice), and 1880. Finally, in 1881, a group of four bomb-throwing assassins finally killed him
(The New York Times headline: "EXPRESSIONS OF SYMPATHY.; MESSAGES OF CONDOLENCE BEING SENT FROM ALL PARTS OF THE WORLD-- ENGLISH AND GERMAN PRINCES TO ATTEND THE FUNERAL. March 15, 1881, Wednesday, Page 2. BERLIN, March 14.--The sensation caused here by the assassination of the Czar is indescribable. The Emperor William wept bitterly at the terrible event, and is filled with the deepest sorrow. The imperial Princes remained with him until 2 o'clock this morning endeavoring to console him."