A vast array of naturally occurring bioactive chemicals with substantial therapeutic potential is produced by the remarkable diversity of species found in marine habitats. The utilization of bioactives generated from marine sources to treat tumors and malignancies of the neurons is the main topic of this chapter. Marine chemicals provide new methods of action and focused therapeutic benefits as traditional cancer treatments encounter more difficulties, such as medication resistance and adverse effects. In preclinical research, bioactive peptides, polysaccharides, alkaloids, and other metabolites obtained from marine organisms such as algae, sponges, and microbes have shown encouraging anticancer qualities. Species like red algae, which have thousands of undiscovered variants, are noteworthy because they offer a significant reservoir of potentially useful chemicals. This chapter examines recent research results, mechanisms of action, and possible avenues for marine bioactives to support novel brain cancer treatment strategies.