  The dynamics of galactic nuclei reflects the presence of supermassive black
holes (SBHs) in many ways. Single SBHs act as sinks, destroying a mass in stars
equal to their own mass in roughly one relaxation time and forcing nuclei to
expand. Formation of binary SBHs displaces a mass in stars roughly equal to the
binary mass, creating low-density cores and ejecting hyper-velocity stars.
Gravitational radiation recoil can eject coalescing binary SBHs from nuclei,
resulting in offset SBHs and lopsided cores. We review recent work on these
mechanisms and discuss the observable consequences.
