Is a voltage regulator considered an IC?
I am not going into the discussion at what point a circuit is complex enough to be called an integrated circuit. 

I can imagine that a voltage regulator looks so simple (just three wires) that it is difficult to see why it would be called an IC. Not much different from transistor: it has about the same size and same number of connections!
So I looked on the WWW a for diagram of what is inside an LM317 and a 7805. Two very common voltage regulators. This gives a better notion of the complexity of those circuits.

LM317:


7805: