The Black Hole of Calcutta is a widely known example of what can only be considered a corporate concentration camp of the (at the time privately owned) British East India Company...
That is a bad example indeed. The event of the Black Hole of Calcutta, where soldiers were rounded into a tiny dungeon which few survived, was perpetrated against British soldiers working for the East India Company by the governor of Bengal, Siraj ud-Daulah.
Corporations have nuclear power plants that can be just as dangerous. Corporations can feed the masses miss-information, that may lead to destabilisation of a society by making them vote for the wrong person.
Corporations build unsave factories that kill 1000s when collapsing (see Bangladesh). Corporations will add addictive substances to food and sigaretes you increase sales, in the process killing millions.