Thyroid cancer is a common malignancy with generally excellent prognosis. While the majority of thyroid malignancies are differentiated follicular cell-derived tumors which respond excellently to treatment, anaplastic thyroid cancer is an extremely aggressive tumor and has limited treatment options. Surgical resection is the mainstay of thyroid cancer treatment. The role and choice of adjuvant medical therapies depend on stage and risk factors, cell of origin, histologic subtype, and molecular signature. Parathyroid carcinoma is a rare malignancy that accounts for less than 1% of cases of primary hyperparathyroidism. Preoperative diagnosis should be suspected based on clinical features, imaging, and laboratory findings. Final diagnosis is difficult to confirm even with final histologic evaluation. Surgery is the only potentially curative treatment option. This chapter provides an overview of the evaluation of thyroid nodules, thyroid malignancies, and their management, as well as a review of the evaluation and management of parathyroid carcinoma.