  The Hadamard product of two power series is obtained by multiplying them
coefficientwise. In this paper we characterize those power series that act as
Hadamard multipliers on all weighted Dirichlet spaces on the disk with
superharmonic weights, and we obtain sharp estimates on the corresponding
multiplier norms. Applications include an analogue of Fej\'er's theorem in
these spaces, and a new estimate for the weighted Dirichlet integrals of
dilates.
