  We investigate the implications of the existence of Killing spinors in a
spacetime. In particular, we show that in vacuum and electrovacuum a Killing
spinor, along with some assumptions on the associated Killing vector in an
asymptotic region, guarantees that the spacetime is locally isometric to the
Kerr or Kerr-Newman solutions. We show that the characterisation of these
spacetimes in terms of Killing spinors is an alternative expression of
characterisation results of Mars (Kerr) and Wong (Kerr-Newman) involving
restrictions on the Weyl curvature and matter content.
