  A growing number of early Be stars discovered in X-ray surveys exhibit X-ray
luminosities intermediate between those of normal stars and those of most
Be/X-ray binaries in quiescence. Their X-ray spectra are also much harder than
those of shocked wind OB stars and can be best fitted by a thin thermal plasma
with T ~ 10^8 K, added to a cooler and much fainter thermal component. An iron
line complex including a fluorescence component is detected in many cases.
There is no evidence for coherent pulsations in any of these systems but strong
variability on time scales as short as 100 s is usually observed. Large
oscillations with quasi-periods of the order of one hour or more are detected
in the X-ray light curves of several sources, but have so far failed to prove
to be strictly periodic. The optical and X-ray properties of these new objects
strikingly resemble those of the so far unique and enigmatic Be star Gamma-Cas
and define a new class of X-ray emitters. We discuss the possible origin of the
X-ray emission in the light of the models proposed for Gamma-Cas, magnetic
disc-star interaction or accretion onto a compact companion object -- neutron
star or white dwarf.
