  The notion of U(1) lepton number (which may only be softly broken) is applied
to models of dark matter which interacts with leptons. Previous scotogenic
models of Majorana or Dirac neutrino mass are shown to be derivable in this
framework without additional symmetries. Only complete renormalizable theories
are considered. An explicit class of models with $Z_n$ ($n \geq 5$) lepton and
dark symmetry for Dirac neutrinos is derived, as well as an example of $Z_3$
dark symmetry.
