The Collaborative International Dictionary of English v.0.48:

Inheritor \In*her"it*or\, n.
   One who inherits; an heir.
   [1913 Webster]

         Born inheritors of the dignity.          --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inheritor
    n 1: a person who is entitled by law or by the terms of a will
         to inherit the estate of another [syn: heir, inheritor,
         heritor]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "inheritor":
   apparent heir, backup man, beneficiary heir, breed, brood,
   children, coparcener, descendant, descendants, descent, family,
   fideicommissary heir, fiduciary heir, fruit, grandchildren,
   great-grandchildren, heir, heir apparent, heir expectant,
   heir general, heir in tail, heir of entail, heir of inventory,
   heir of line, heir portioner, heir presumptive, heir whatsoever,
   heiress, heirs, heritor, hostages to fortune, inheritors,
   inheritress, inheritrix, issue, joint heir, kids, lineage,
   little ones, new generation, next in line, offspring, posterity,
   presumptive heir, progeny, remainderman, replacement, reversioner,
   rising generation, seed, sons, succession, successor, treasures,
   younglings, youngsters