  We discuss recent searches for new physics using high-energy atmospheric
neutrino data from IceCube, namely sterile neutrinos with masses in the range
$\Delta m^2 = 0.01$ eV$^2$ - 10 eV$^2$, and non-standard interactions (NSI) in
the $\nu_\mu - \nu_\tau$ sector. We also present a brief review of the current
status of NSI theory and phenomenology.
