Many would argue there are 2-3 agencies that fit this description but the most famous and clear cut is the NRO: https://en.m.wikipedia.org/wiki/National_Reconnaissance_Offi...
Not just CIA. Whenever military industrial complex or bankers want a make over, defers litigation risks or just conceal ownership, they just create a subsidiary, spun it off with another name and/or hide the everything behind client attorney privileges.
It also gives the public a memory wipe. Very clever technique indeed.