  A Chandra ACIS-S imaging observation of the nearby galaxy M81 (NGC 3031)
reveals 9 luminous soft X-ray sources. The local environments, X-ray spectral
properties, and X-ray light curves of the sources are presented and discussed
in the context of prevailing physical models for supersoft sources. It is shown
that the sample falls within expectations based on population synthesis models
taken from the literature though the high observed luminosities (L~2.0e36 to
\~3.0e38 erg/s in the 0.2-2.0 keV band) and equivalent blackbody temperatures
T~40 to 80 eV) place the brightest detected M81 objects at the high luminosity
end of the class of supersoft sources defined by previous ROSAT and Einstein
studies of nearby galaxies. This is interpreted as a natural consequence of the
higher sensitivity of Chandra to hotter and more luminous systems. Most of the
sources can be explained as canonical \ssss, accreting white dwarfs powered by
steady surface nuclear burning, with X-ray spectra well-fit by hot white dwarf
local thermodynamic equilibrium atmosphere models. An exceptionally bright
source is scrutinized in greater detail as its estimated bolometric luminosity,
L~1.5e39 erg/s, greatly exceeds theoretical estimates for supersoft sources.
This source may be beyond the stability limit and undergoing a phase of mass
outflow under extreme conditions. Alternatively, a model in which the observed
X-ray spectrum arises from an accretion disk around a blackhole of mass
\~1200/sqrt(cos(i)) solar masses (viewed at an inclination angle i) cannot be
excluded.
