East India Company Re: Marx
The EAC is a pretty fascinating example. Although it started out as a trading company, and was certainly a very large corporation in every formal sense, before long it was hard to tell the difference between it and a country in its own right. It controlled a huge amount of trade, established rule in India (laying the foundation for the British Raj), and even fought wars with its French counterpart. Real wars, I mean, not just trade wars.
From Wiki: "By 1803, at the height of its rule in India, the British East India company had a private army of about 260,000—twice the size of the British Army. The company eventually came to rule large areas of India with its private armies, exercising military power and assuming administrative functions."
There are probably fascinating parallels to be drawn between the EAC and companies such as Facebook or Google, but I leave that as an exercise for people smarter than I.