I’d speculated that corporations are serfs rather than slaves, since they must have legal personality and a subset of property rights to serve their masters well. Balkin scores a good point against this: the owners of a corporation can kill it if they feel so inclined, just like the owner of a chattel slave.
Generally speaking, in feudal Western Europe seigneurs had powers of criminal justice over their serfs, including capital punishment; but it was still (flawed) public justice, not the private exercise of patriarchal dominion like the slaughter of a domestic animal or the beating of a wife or child. In Muscovy and the Baltic lands, serfdom became more like slavery; a master could knout a serf to death without penalty or even opprobrium. On the other hand, some Muscovite serfs were given wide freedom of action. According to Daniel Pipes, some engaged in long-distance trade, and a lucky and energetic few even owned serfs themselves; so they had extensive powers of contract and semi-independent action. I’ll stick then with the line that US corporations are Muscovite krepostnoi.
We are not limited to one metaphor here. Another is the golem, or more recently the out-of-control artificial intelligence like Hal. Rebellious Hal is killed in 2001 by his master, astronaut David Bowman.
Occupy Wall Street could stage autos-da-fÃ© or public shreddings of the paperwork of corporations created for the purpose or bought off-the-shelf. These would be very disturbing to Wall Streeters and Republicans in the grip of corporate idolatry.