  In this brief review, we examine the theoretical consistency and viability of
phantom dark energy. Almost all data sets from cosmological probes are
compatible with dark energy of the phantom variety (i.e., equation-of-state
parameter $w<-1$) and may even favor evolving dark energy, and since we expect
every physical entity to have some kind of field description, we set out to
examine the case for phantom dark energy as a field theory. We discuss the many
attempts at frameworks that may mitigate and eliminate theoretical pathologies
associated with phantom dark energy. We also examine frameworks that provide an
apparent measurement $w<-1$ while avoiding the need for a phantom field theory.
