This chapter provides a practical overview of frequently used markers in the diagnosis and differential diagnosis of both common and rare neoplasms of the thyroid and parathyroid glands, with a specific focus on papillary thyroid carcinoma and its mimickers. The chapter contains 28 questions; each question is addressed with a table, concise note, and representative pictures if applicable. In addition to the literature review, the authors have included their own experience and tested numerous antibodies reported in the literature. The most effective diagnostic panels of antibodies have been recommended for many entities, such as CK19, HBME-1, and galectin-3 being suggested as the best diagnostic panel for identifying papillary thyroid carcinoma. Furthermore, immunophenotypes of normal thyroid tissue have been described, which tends to be neglected in literature.