  An isolated horizon (IH) is a null hypersurface at which the geometry is held
fixed. This generalizes the notion of an event horizon so that the black hole
is an object that is in local equilibrium with its (possibly) dynamic
environment. The first law of IH mechanics that arises from the framework
relates quantities that are all defined at the horizon.
  IHs have been extensively studied in Einstein gravity with various matter
couplings and rotation, and in asymptotically flat and asymptotically anti-de
Sitter (ADS) spacetimes in all dimensions $D\geq3$. Motivated by the
nonuniqueness of black holes in higher dimensions and by the black-hole/string
correspondence principle, we devote this thesis to the extension of the
framework to include IHs in string-inspired gravity models, specifically to
Einstein-Maxwell-Chern-Simons (EMCS) theory and to Einstein-Gauss-Bonnet (EGB)
theory in higher dimensions.
  The focus is on determining the generic features of black holes that are
solutions to the field equations of the theories under consideration. We obtain
various results for non-extremal, extremal and supersymmetric IHs in EM-CS
theory, and for non-rotating IHs in EGB theory.
  (An extended abstract is given in the PDF file.)
