Disclosed herein are monoclonal antibodies targeting specific tau epitopes, particularly, phosphorylated tau epitopes. Also disclosed are methods of detecting tau protein in a subject, comprising performing an assay using the antibodies or antigen binding fragments thereof on the subject or on a biological sample obtained from the subject. Assay kits containing the disclosed antibodies are also provided. Further, methods of treating or preventing a tauopathy in a subject by administering to the subject tau antibodies or antigen-binding fragments thereof are provided.