  We present a study of the infrared properties of 4922 spectroscopically
confirmed massive stars in the Large and Small Magellanic Clouds, focusing on
the active OB star population. Besides OB stars, our sample includes yellow and
red supergiants, Wolf-Rayet stars, Luminous Blue Variables (LBVs) and
supergiant B[e] stars. We detect a distinct Be star sequence, displaced to the
red, and find a higher fraction of Oe and Be stars among O and early-B stars in
the SMC, respectively, when compared to the LMC, and that the SMC Be stars
occur at higher luminosities. We also find photometric variability among the
active OB population and evidence for transitions of Be stars to B stars and
vice versa. We furthermore confirm the presence of dust around all the
supergiant B[e] stars in our sample, finding the shape of their spectral energy
distributions (SEDs) to be very similar, in contrast to the variety of SED
shapes among the spectrally variable LBVs.
