  We discuss the impact of strange hadrons, in particular hyperons, on the
gross features of compact stars and on core-collapse supernovae. Hyperons are
likely to be the first exotic species which appears around twice normal nuclear
matter density in the core of neutron stars. Their presence largely influences
the mass-radius relation of compact stars, the maximum mass, the cooling of
neutron stars, the stability with regard to the emission of gravitational waves
from rotation-powered neutron stars and the possible early onset of the QCD
phase transition in core-collapse supernovae. We outline also the constraints
from subthreshold kaon production in heavy-ion collisions for the maximum
possible mass of neutron stars.
