  We compute the charm quark mass in lattice QCD and compare different
formulations of the heavy quark, and quenched data to that with dynamical sea
quarks. We take the continuum limit of the quenched data by extrapolating from
three different lattice spacings, and compare to data with two flavours of
dynamical sea quarks with a mass around the strange at the coarsest lattice
spacing. Both the FNAL and ALPHA formalism are used. We find the different
heavy quark formulations have the same continuum limit in the quenched
approximation, and limited evidence that this approximation overestimates the
charm quark mass.
