  Over the last ~5 years we have identified ~35 black hole candidates (BHCs) in
M31 from their X-ray spectra. Our BHCs exhibited 0.3--10 keV spectra consistent
with the X-ray binary (XB) hard state, at luminosities that are above the upper
limit for neutron star (NS) XBs. When our BHC spectra were modeled with a disk
blackbody + blackbody model, for comparison with bright NS XBs, we found that
the BHCs inhabited a different parameter space to the NS XBs. However, BH XBs
may also exhibit a thermally dominated (TD) state that has never been seen in
NS XBs; this TD state is most often observed in X-ray transients. We examined
the ~50 X-ray transients in our Chandra survey of M31, and found 13 with
spectra suitable for analysis. We also examined 2 BHCs outside the field of
view of our survey, in the globular clusters B045 and B375. We have 42 strong
BHCs, and 8 plausible BHCs that may benefit from further observation. Of our 15
BHCs in globular clusters, 12 differ from NS spectra by >5 sigma. Due to
improvements in our analysis, we have upgraded 10 previously identified
plausible BHCs to strong BHCs. The mean maximum duty cycle of the 33 X-ray
transients within 6' of M31* was 0.13; we estimate that >40% of the XBs in this
region contain BH accretors. Remarkably, we estimate that BHCs contribute >90%
of those XBs >1 E+38 erg/s.
