Stolypin was assassinated in September 1911 whilst attending an opera in Kiev by a left-wing revolutionary.
The Tsar was also present at the opera.
The revolutionary left-wing groups had clearly not forgiven him for the harsh repression he used in 1906 and 1907 and for his "coup" in 1907 when he changed the voting system.
However, it is said that the Tsar was actually quite pleased to be rid of Stolypin as many in court were increasingly unhappy about his reforms.
In fact, Bogrov who assassinated Stolypin, was an SR that worked for the Okhrana and it is not entirely clear who ordered Bogrov to murder Stolypin.