  We consider the possibility of an axion-like particle (ALP) that is a ghost,
with wrong-sign kinetic and mass terms. Such an ALP can arise as the partner to
an ordinary particle in theories with higher-derivative quadratic terms. We
compute the photon regeneration probability in light-shining-through-wall
experiments and show that the presence of such a ghostly ALP can lead, in
principle, to discernible effects.
