Giant cells are formed by the union of several monocytes or macrophages which undergo a defined set of intercellular interactions that ultimately results in a multinucleated cell with a single cytoplasmic compartment. Giant cells are not only pathologic, there are even physiologic giant cells such as osteoclast, megakaryocytes, and trophoblast that helps in maintaining normal repair and remodeling process in the body. There are various classifications and theories for the formation of giant cells. Some of these giant cells act as a characteristic histopathologic feature in oral lesions and aid in diagnosis. In the field of challenging diagnosis, these characteristic features can provide a clue for diagnosing some oral lesions. On this background, the article was attempted to review various types of giant cells, their formation, and giant cell lesions of the oral cavity with basic information about their clinical, radiologic, histopathological features, and treatment planning.