How was Cicero killed?

Cicero was killed by Herennius (a centurion) and Popilius (a tribune).

He was proscribed (identified as an enemy of the State) by the Second Triumvirate - Octavian (later known as Augustus), Marcus Aemilius Lepidus, and Mark Antony. However, it is said that Octavian was opposed to adding Cicero to the list of the proscribed.