  We summarize multiwavelength properties of a sample of galaxies in the CDF-N
and CDF-S whose Spectral Energy Distributions (SEDs) exhibit the characteristic
power-law behavior expected for AGN in the Spitzer/IRAC 3.6-8micron bands. AGN
selected this way tend to comprise the majority of high X-ray luminosity AGN,
whereas AGN selected via other IRAC color-color criteria might contain more
star-formation dominated galaxies. Approximately half of these IR power-law
galaxies in the CDF-S are detected in deep (1Ms) Chandra X-ray imaging,
although in the CDF-N (2Ms) about 77% are detected at the 3sigma level. The
SEDs and X-ray upper limits of the sources not detected in X-rays are
consistent with those of obscured AGN, and are significantly different from
those of massive star-forming galaxies. About 40% of IR power-law galaxies
detected in X-rays have SEDs resembling that of an optical QSO and morphologies
dominated by bright point source emission. The remaining 60% have SEDs whose UV
and optical continuum are much steeper (obscured) and more extended
morphologies than those detected in X-rays. Most of the IR power-law galaxies
not detected in X-rays have IR (8-1000micron above 10^12Lsun, and X-ray (upper
limits) to mid-IR ratios similar to those of local warm (ie, hosting an AGN)
ULIRGs. The SED shapes of power-law galaxies are consistent with the obscured
fraction (4:1) as derived from the X-ray column densities, if we assume that
all the sources not detected in X-rays are heavily absorbed. IR power-law
galaxies may account for between 20% and 50% of the predicted number density of
mid-IR detected obscured AGN. The remaining obscured AGN probably have
rest-frame SEDs dominated by stellar emission.
