  Models of the continuum radiation from accreting hot plasmas typically assume
that the plasma heating mechanism produces energetic particles distributed in
energy either as a Maxwellian (the ``thermal'' models) or as an extended power
law (the ``non-thermal'' models). The reality, however, is that neither
description is probably accurate. In other astrophysical contexts where we have
been able to observe the actual particle energy distributions, e.g. solar
system plasmas, and in many particle acceleration theories, the heating
mechanism supplies only some fraction of the available energy to very energetic
particles. The remainder goes into producing lower energy particles which
settle into a quasi-Maxwellian energy distribution. Here, I review the
arguments for ``thermal'' versus ``non-thermal'' plasmas in accreting black
hole systems and discuss the physics and emission properties of ``hybrid''
plasmas, where the particle distribution energy is approximately a Maxwellian
plus a power law tail. Using results from a new emission code, I then show that
such plasmas may be relevant to explaining recent observations, particularly
those of Galactic black hole candidates in their soft state.
