  We investigate the contributions of quantum fields to black hole entropy by
using a cutoff scale at which the theory is described with a Wilsonian
effective action. For both free and interacting fields, the total black hole
entropy can be partitioned into a contribution derived from the gravitational
effective action and a contribution from quantum fluctuations below the cutoff
scale. In general the latter includes a quantum contribution to the Noether
charge. We analyze whether it is appropriate to identify the rest with horizon
entanglement entropy, and find several complications for this interpretation,
which are especially problematic for interacting fields.
