This chapter reviews various fillers from natural resources as alternatives to conventional fillers in natural rubber composites and nanocomposites. The aim is to provide a comprehensive overview of the mechanical, morphological, and thermal properties of natural rubber-based composites and nanocomposites. The drawbacks of most natural fillers are discussed, including the influence of hydroxyl groups on the surface of the natural fillers and their compatibility issues with the rubber matrix. Additionally, the characterization techniques used to assess the impact of natural fillers on mechanical properties, along with the mechanisms of their performance reduction, are reviewed. This review is expected to give progress in minimizing the problem between the natural filler and natural rubber matrix. It can be done by reviewing the most recent study in this work.