Domitian (51–96) was the ruthless Roman emperor under whose reign the apostle John was sent to the isle of Patmos.
When John said these things, he was on the island of Patmos, condemned by Caesar Domitian to labor in the mines. When John had grown old, he thought that he would eventually meet his end through suffering. However, Domitian was killed and all his judgments were thrown out. Victorinus (c. 280, W), 3.353
After an interval of some years from the death of Nero, there arose another tyrant [Domitian], who was no less wicked. His government was exceedingly hateful. For a very long time, he oppressed his subjects and reigned in security—until at length he stretched forth his unholy hands against the Lord. Having been instigated by evil demons to persecute the righteous people, he was then delivered into the power of his enemies and suffered due punishment. That he was murdered in his own palace was not sufficient vengeance; the very memory of his name was erased. Lactantius (c. 320, W), 7.302