We propose a new and unique dark matter candidate: $ ilde{100}$ eV to $ ilde{10}$ keV sterile neutrinos produced via lepton number-driven resonant MSW (Mikheyev-Smirnov-Wolfenstein) conversion of active neutrinos. This new candidate is a nonthermal sterile neutrino, which is produced via resonant active-sterile neutrino transformations during Big Bang Nucleosynthesis (BBN). The sterile neutrino is a new type of dark matter candidate that is not yet observed in the universe. The production mechanism of this new candidate is different from the traditional thermal dark matter candidates, which are produced via the Big Bang. The nonthermal sterile neutrino is a new and unique dark matter candidate that can explain the observed dark matter abundance in the universe.