  We extract the imaginary part of the heavy-quark potential using
classical-statistical simulations of real-time Yang-Mills dynamics in classical
thermal equilibrium. The $r$-dependence of the imaginary part of the potential
is extracted by measuring the temporal decay of Wilson loops of spatial length
$r$. We compare our results to continuum expressions obtained using hard
thermal loop theory and to semi-analytic lattice perturbation theory
calculations using the hard classical loop formalism. We find that, when
plotted as a function of $m_D r$, where $m_D$ is the hard classical loop Debye
mass, the imaginary part of the heavy-quark potential shows little sensitivity
to the lattice spacing at small $m_D r \lesssim 1$ and agrees well with the
semi-analytic hard classical loop result. For large quark-antiquark
separations, we quantify the magnitude of the non-perturbative long-range
corrections to the imaginary part of the heavy-quark potential. We present our
results for a wide range of temperatures, lattice spacings, and lattice
volumes. This work sets the stage for extracting the imaginary part of the
heavy-quark potential in an expanding non-equilibrium Yang Mills plasma.
