细胞骨架（英语：Cytoskeleton）一般是指细胞内细胞质中的由蛋白质构成的纤维的网络结构。尽管其名称所暗示的骨架是稳定的，但它是一个动态结构，其中有一部分是不断的被破坏，更新或新建的。

在生命的所有生物领域（古菌，细菌，真核生物）的细胞里都有细胞骨架被发现（特别是在所有真核细胞，包括人类，动物和植物细胞，甚至于噬菌体中都有细胞骨架被发现）。不同生物体的细胞骨架系统是由相似的蛋白质组成。但是，细胞骨架的结构，功能和动态行为可以是非常不同的，这取决于生物体和细胞类型。类似地，在同一细胞类型内细胞骨架的结构，动态行为和功能可以通过与其他蛋白质和网络的以前的历史关联发生变化。

In all cells of all domains of life (archaea, bacteria, eukaryotes) a cytoskeleton is found (notably in all eukaryotic cells, which include human, animal, fungal and plant cells). The cytoskeleton can be referred to as a complex network of interlinking filaments and tubules that extend throughout the cytoplasm, from the nucleus to the plasma membrane The cytoskeletal systems of different organisms are composed of similar proteins. In eukaryotes, the cytoskeletal matrix is a dynamic structure composed of three main proteins, which are capable of rapid growth or disassembly dependent on the cell's requirements at a certain period of time.