Traditionally, Hurthle cell neoplasms (HCNs) have been classified into benign (Hurthle cell adenoma—HCA) and malignant (Hurthle cell carcinoma—HCC). In 2000, a third category was added; HCN of uncertain malignant behavior. In the same year, HCNs were classified by some authors into HCA, HCC, and Hurthle cell papillary carcinoma (HCPC) based on data from molecular studies. Hurthle cell carcinoma has been long considered as a subgroup of follicular thyroid cancer (FTC) and was classified as such by the World Health Organization (before 2017). However, stemming from the more aggressive clinical behavior, different oncogene expression, and specific molecular pathogenesis, HCC has been considered by some authors to be a distinctive subset of differentiated thyroid cancer (DTC), different from FTC. More recently, based on the degree of capsular invasion and vascular invasion, HCC has been subclassified into two groups: minimally invasive (miHCC) and widely invasive (wiHCC) Hurthle cell carcinoma. The new classification in the fifth edition (2022) of the “WHO Classification of Endocrine and Neuro-endocrine Tumors” that relates to the thyroid gland has divided thyroid tumors into several new categories and emphasized that HCC is a separate entity of DTC and not a subtype of FTC. In the 2022 WHO classification, “oncocytic cell” has replaced “Hürthle cell.” Accordingly, oncocytic adenoma and oncocytic carcinoma of the thyroid are the new names for Hürthle cell adenoma (HCA) and Hürthle cell carcinoma (HCC), respectively. This chapter discusses the different pathological classifications of oncocytic (Hurthle cell) neoplasms, including the most recent (2022) WHO classification of thyroid tumors, and the controversies related to each.