This paper investigates the evolution and performance of advanced bolt and dowel-based shear connectors in modular and composite construction systems, focusing on steel-concrete composites, precast shear walls, modular beams, and demountable frames. Key innovations, such as high-strength friction-grip bolts (HSFGBs), threaded stud connectors, Y-stud bolts, and hybrid nut-bolt systems, are examined for their load transfer efficiency, shear resistance, and assembly ease. The study analyzes frictional mechanisms, dynamic performance, and the effectiveness of single vs. double nut configurations in structural joints. Blind bolts, reinforced hybrid bolts, and locking nuts are assessed for demountable applications. Coupler systems, including cylindrical and pretensioned bolts, are evaluated for mitigating deformations and addressing thread penetration. Innovative shear connectors, such as clamping connectors and yielding pockets, are also explored for their impact on slip capacity, stiffness, and fatigue resistance. Future research focuses on improving ductility, energy dissipation, rapid assembly, and sustainability, advancing the reusability and adaptability of modular and composite systems for more resilient structures.