One of the runner-ups to be the 3rd Emperor but did not succeed.

Lucius Aelius Seianus (or Sejanus) (20 BC – October 18, 31 AD) was an ambitious soldier, friend and confidant of Tiberius, and for a time the most influential and feared citizen of Rome.

Sejanus: His Fall, a 1603 play by Ben Jonson, is a tragedy about Lucius Aelius Seianus, the favorite of the Roman emperor Tiberius. It was possibly an allegory of James I and his corrupt court.