The Thirty Tyrants is an ancient example of the deep state

With Spartan support, the Thirty established an interim government in Athens. The Thirty were concerned with the revision and/or erasure of democratic laws inscribed on the wall next to the Stoa Basileios. Consequently, the Thirty reduced the rights of Athenian citizens in order to institute an oligarchical regime. The Thirty appointed a council of 500 to serve the judicial functions formerly belonging to all the citizens. However, not all Athenian men had their rights removed. In fact, the Thirty chose 3,000 Athenian men "to share in the government". These hand-selected individuals had the right to carry weapons, to have a jury trial, and to reside within city limits. The list of the selected 3,000 was consistently revised. Although little is known about these 3,000 men - for a complete record was never documented - it is hypothesized that the Thirty appointed these select few as the only men the Thirty could find who were devotedly loyal to their regime. The majority of Athenian citizens did not support the rule of the Thirty.

https://en.wikipedia.org/wiki/Thirty_Tyrants