Sejanus

On September 18, 31, Sejanus, Roman head of he praetorian guard, was executed. From the article:

"Lucius Aelius Seianus or Sejanus (20 BCE-31 CE) was the commander of the praetorian guard under the emperor Tiberius (14-37 CE). Coming from an obscure equestrian family, he managed to become one of the closest advisor of Tiberius, hoping to become his successor or a regent to a young heir. After the death of Drusus, Tiberius' son, he started to persecute all his possible rivals, a task he made easier by driving Tiberius into paranoia and convincing him to retire to Capri in a self-imposed exile. In the end, though, Tiberius grew suspicious of his minister and his ambitions, and ordered his execution. Sejanus' children and many of his friends fell with him in a bloody political purge."