<p>Printheads are the cornerstone of material extrusion 3D printing systems, now capable of processing virtually any material — organic or inorganic. Multimaterial capabilities have further expanded their versatility, enabling coextrusion, mixing and material switching. Advanced multifunctional printhead features allow for nozzle size and shape adjustments, printhead rotation and in situ property modulation. These improvements enable unprecedented design complexity, higher throughput and the fabrication of intricate material compositions across multiple length scales. Applications span from architected metamaterials with tunable properties to functional tissue from living cells and soft robotics with integrated sensing. This Review provides a comprehensive overview of this rapidly evolving field, introducing eight archetypal printhead categories and their hybrids. It explores their role in materials design, ability to overcome processing limitations and impact on emerging applications. Additionally, it identifies open challenges and offers an outlook on the future of multimaterial 3D printing.</p>