Spoilers for the whole show!
In Person of Interest, near the end of season 2, the Machine forms and uses the Thornhill persona and the Thornhill Corporation, which manages a workaround for the Machine's memories being deleted.
At the end of season 3, the Machine is forced into hiding and the Samaritan "era" begins, which lasts for more than a season.
At the end of season 4, devices which are ostensibly power boxes produced and distributed by Thornhill Utilities are used to save the Machine.
At the end of season 5, some employees of the Thornhill Corporation save Mr. Reese and Detective Fusco.
The question is why is this corporation allowed continued existence, instead of being exploited by Samaritan (it could have order investigations of it, it could have turned the people already working there, tried infiltrating it, or, failing all that, it could have just destroyed it)?
Team Machine is protected by hacked Samaritan servers installed by Root and her team, and the Machine itself can hide from Samaritan, but I can't recall any discussions of hiding an entire corporation.