Provided are anti-PD-1 antibodies, and antigen binding fragments thereof. Also provided are isolated nucleic acid molecules that encode the anti-PD-1 antibodies or antigen binding fragments thereof, related expression vectors, and host cells. Provided are methods of making anti-PD-1 antibodies, and antigen binding fragments thereof. Also provided are related pharmaceutical compositions and methods of their use to treat subjects. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.