The International Linear Collider (ILC) offers a number of unique opportunities for searching dark sector particles in e$^+$e$^-$ collisions. The collider program itself will offer important capabilities, including precision measurements in the Higgs sector and direct searches based on the mono-photon signature. With extreme intensities of the high-energy electron and positron beams, the ILC will also enable new fixed-target measurements, both beam dump experiments and dedicated experiments using extracted beams. Described in this contribution are the expectations for these programs, which address various possible dark sector portals.