We have compiled the first all-sky mid-infrared variable-star catalog
based on Wide-field Infrared Survey Explorer (WISE) five-year survey
data. Requiring more than 100 detections for a given object, 50,296
periodic variables are discovered, of which 34,769 (69\%) are
new. Most are located in the Galactic plane and near the equatorial
poles. A method to classify variables based on their mid-infrared
light curves is established using known variable types in the General
Catalog of Variable Stars. Careful classification of the new variables
results in a tally of 21,427 new EW-type eclipsing binaries, 5654
EA-type eclipsing binaries, 1312 Cepheids, and 1231 RR Lyraes. By
comparison with known variables available in the literature, we
estimate that the misclassification rate is 5\% and 10\% for short-
and long-period variables, respectively. A detailed comparison of the
types, periods, and amplitudes with variables in the Catalina catalog
shows that are independently obtained classifications parameters are
in excellent agreement. This enlarged sample of variable stars will
not only be helpful to study Galactic structure and extinction
properties, they can also be used to constrain stellar evolution
theory and as potential candidates for the {\sl James Webb Space
Telescope