By definition, an indolent course lacking recurrence or metastasis is the clinical hallmark of “benign” tumors. However, for oncocytic/Hurthle cell neoplasms (HCNs), this concept is confused by the occasional reports of recurrence or metastasis in histologically proven oncocytic adenomas (Hurthle cell adenomas—HCAs). There has also been a considerable controversy in the literature as to whether oncocytic carcinoma of the thyroid (Hurthle cell carcinoma—HCC) has a similar or more aggressive clinical behavior as compared to follicular thyroid carcinoma. This diversity of perspectives highlights the complexity of understanding and managing oncocytic/Hurthle cell carcinoma, warranting further investigation and consensus-building to improve patient outcomes. This chapter discusses the demographic data and clinical presentation of oncocytic/Hurthle cell neoplasms as well as their clinical behavior as compared to follicular thyroid carcinoma and papillary thyroid carcinoma.