In tissue engineering cells are combined with biomaterial scaffolds and stimuli to build implantable constructs and tissue models. These stimuli include biochemical and biophysical cues that are essential for cell function. Biophysical stimuli can be delivered by bioreactor systems, particularly mechanical cues. Furthermore, bioreactors are essential to achieve effective mass transfer of oxygen and nutrients, especially in large tissue constructs. Hence, bioreactors become powerful tools for tissue engineering applications like engineering of constructs for transplantation, recellularization of decellularized tissues and organs, or cell expansion for cell therapies. There are important design considerations to bear in mind when building a bioreactor, and several types, each with its advantages and disadvantages, are available. The present chapter offers an overview of bioreactors used in TERM applications.