Cancer diseases account for about 15% of deaths globally right now, and the percentage may increase in the future. There are more than 100 types of cancer, and each of them is distinct in its origin, microenvironment, growth, metastasis, and signalling pathways. Cancer stem cells are the specialised cells that make cancer more aggressive and difficult to treat. Moreover, cancer aetiology may exist at the genomic, proteomic, or habitat level in any combination. Hence, a unanimous treatment protocol for the different cancers is an uphill task at the present juncture. In this context, this review aims to provide a comprehensive reappraisal concisely of anti-apoptotic proteins, which are shown to be overexpressed in most cancers, if not all, and to forthrightly rationalise the apoptotic proteins as potential biomarkers and druggable targets of the cancers by effectively killing cancer stem cells.