Biomedical applications of plasmonic metal nanostructures represent new and exciting directions of research and development. For instance, photothermal ablation therapy (PTA) based on metal nanomaterials has been actively explored for treating cancer with encouraging success. PTA relies on heat generated from light for destroying cancer cells and thus requires strong optical absorption and high efficiency of photothermal conversion. Desired metal nanostructures for PTA should have strong and tunable SPR, low toxicity, ease of delivery, and convenience for bioconjugation for actively targeting cancer cells. Nanostructures of noble metals, for example, gold and silver, show great promise for PTA applications, including nanoparticles, nanorods, nanoshells, nanocages, and hollow nanospheres. Among these structures, hollow gold nanospheres exhibit a unique combination of small size, spherical shape, and strong, narrow, and tunable SPR. This Perspective highlights the importance of shape control in determining the optical and photothermal properties of metal nanostructures for PTA applications.