<p>This Special Issue explores significant research on fiber-reinforced thermoplastic composites including advancements in material development process optimization sustainability and multimodal characterization techniques. Featured topics include low-density high-performance composite foams flame-retardant panels and eco-friendly bio-composites using flax and cashew nut shells. This issue also examines optimizing processing methods like hot runner systems and enhancing recycled-fiber composites. These studies offer valuable insights into the evolving landscape of composite materials.</p>