tsaricide

noun2

1. •
   The killing of a tsar.

   • It had been those wishing to unleash a revolution “sooner,” so said the count, who had come to advocate tsaricide. — 2009
2. •
   One who kills a tsar.

   • Thus, Boris Godunov suffered from a “miraculous” conflation of two incompitable myths: that he was a tsaricide, and that the real Dmitry still lived. — 2006