Cancer represents an intricate challenge in the health sector globally. Effectively addressing various types of cancer requires a deep comprehension of how different cells and elements within the tumor microenvironment behave. T cells and their subcategories stand at the vanguard of the battle against cancer cells. However, T cells can exhibit either anti-tumor or pro-tumor characteristics, depending on the specific characteristics of the tumor microenvironment. Consequently, the behaviors of T cell subtypes can be opposite within different cancer types. Therefore, it is crucial to classify and understand the functions of T cell subtypes within the tumor microenvironment to shed light on the enigma of cancer progression. T cells are generally classified into two main conventional and unconventional T cell categories. Due to the implication of the conventional T cell populations in cancer progression, we focused on the recent insights related to the conventional T cell subtypes as well as their potential roles within tumor microenvironments. Importantly, some subsets of conventional T cells have been discovered during the last decade. Therefore, less is known about their functional characteristics in various cancer types and further profound investigations are essential to cover the related gaps.