Although metals have successfully been used as implants for decades, devices made out of metals do not meet all clinical requirements. For example, metal objects may interfere with some medical imaging systems (computer tomography, magnetic resonance imaging), while their stiffness also differs from natural bone and may cause stress-shielding and over-loading of bone. There has been a lot of development in the field of composite biomaterial research, which has focused to a large extent on biodegradable composites. This overview article reviews the rationale of using glass fiber-reinforced composite–bioactive glass (FRC–BG) in cranial implants. For this overview, published scientific articles with the search term “bioactive glass cranial implant” were collected for having basis to introduce a novel design of composite implant, which contains bioactive glass. Additional scientific information was based on articles in the fields of chemistry, engineering sciences and dentistry. Published articles of the material properties, biocompatibility and possibility to add bioactive glass to the FRC–BG implants alongside with the clinical experience as far suggest that there is a clinical need for bioactive nonmetallic implants. In the FRC–BG implants, biostable glass fibers are responsible for the load-bearing capacity of the implant, while the dissolution of the bioactive glass particles supports osteogenesis and vascularization and provides antimicrobial properties for the implant. Material combination of FRC–BG has been used clinically in cranioplasty and cranio-maxillo-facial implants, and they have been investigated also as oral and orthopedic implants. Material combination of FRC–BG has successfully been introduced to be a potential implant material in cranial surgery.