  We propose a novel mechanism to realize leptogenesis through the Breit-Wigner
resonance of a dark $U(1)_D$ gauge boson $Z_D$, which mediates lepton number
violating annihilations of dark matter (DM) in the context of the scotogenic
model with a $U(1)_D$. The processes occur out of equilibrium and the DM
freezes out lately giving rise to the observed abundance. The CP violation
required for leptogenesis can be achieved by the interference between
tree-level t-channel scattering of DM and the subsequent 1-loop mediated by
$Z_D$, which arises due to the unremovable imaginary part of either the $Z_D$
propagator coming from its self-energy correction or the 1-loop giving rise to
the effective coupling of $Z_D\bar{\nu}\nu$.
