  In the presence of background fields that spontaneously violate Lorentz
invariance, a matter-antimatter asymmetry can be generated even in thermal
equilibrium. In this paper we systematically investigate models of this type,
showing that either high-energy or electroweak versions of baryogenesis are
possible, depending on the dynamics of the Lorentz-violating fields. In
addition to the previously-studied models of spontaneous baryogenesis and
quintessential baryogenesis, we identify two scenarios of interest:
baryogenesis from a pseudo-Nambu-Goldstone boson with weak-scale mass and
intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis
driven by a constant-magnitude vector with a late-time phase transition.
