Various bioplastics produced from waste materials and byproducts from agricultural, agro-food and biofuel industries are introduced in this chapter. As renewable and low carbon-emission substitutes for conventional petroleum-based plastics, bioplastics suffer from high cost since current feedstocks are relatively expensive agricultural raw materials. Using inexpensive wastes and byproducts as feedstocks would be a promising alternative to reduce the cost of production of bioplastics. Two types of bioplastics, thermoplastics from natural macromolecules via chemical modifications or graft polymerizations and bioplastics produced by fermentation of lignocellulose, molasses, whey, oils and other wastes and low-value byproducts from agricultural, agro-food and biofuel industries, are discussed in details. The advantages and drawbacks of using low-value waste materials and byproducts for bioplastics will be summarized based on cost efficiency of production and performance properties of final thermoplastics.