  The Standard Model predicts several rare Higgs boson decay channels, among
which are the decays to a Z boson and a photon, to a low-mass lepton pair and a
photon, and to a meson and a photon. The observation of some of these decays
could open the possibility of studying the CP and coupling properties of the
Higgs boson in a complementary way to other analyses. In addition,
lepton-flavor-violating decays of the observed Higgs boson are searched for,
where an observation would be a clear sign of physics effects beyond the
Standard Model. These proceedings present selected recent results for such
decays based on proton-proton collision data at 13 TeV collected by the ATLAS
experiment in Run 2 of the LHC.
