The state government, which is itself a subsidiary of the United States Government, which is more a form of corporate rule (compare to Commonwealth countries, where the Crown owns most of the land). The only thing missing is shareholders, unless you count people who buy treasury bonds and finance US debt.
The slumlord Uncle Sam
The State I suppose.
Looks like I’m quite out of touch with this whole independent outdoor living thing, so I will shut up now.
Government. If you don’t think the government is the real owner of “your” land, just try not paying the rent.
By the way, one can make some strong economic arguments from this fact. Notably, if land ownership is impossible, so is subsistence farming. All else being equal, this will drive down wages, and hence is a form of corporate welfare.