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Microelectromechanical systems must include large-deflection actuators to create devices which can interact mechanically with their surroundings. Electrostatic actuators with large non-resonant motion require high voltages and large surface areas to produce useful forces. Large-deflection thermal actuators have been fabricated in electroplated metal processes, but the choice of materials is limited, and the high conductivity of metal means these devices need a high current to generate the required heat. Thus, there is a need for a low voltage actuator with a large non-resonant deflection which can be fabricated in integrated circuit compatible surface-micromachining processes. The device described in this paper has a simple, flexible, and reliable design which overcomes the limitations of other actuators. It is a low voltage, medium current thermal actuator which can be designed to move laterally in a controllable, non-resonant motion. Typical actuators are 200 jtm long, 1 8 tm wide, and deflect 1 0 jtm at the tip with a drive current of 5 mA at 5 volts. A wide range of layout geometries allows this type of actuator to be fabricated in any surface-micromachining process that includes a releasable, current-carrying layer. An empirical model is presented to describe the actuator's deflection versus drive current. The model is determined through experimental investigation of polycrystalline silicon devices fabricated in a commercially available surface-micromachining process. Arrays of actuators were fabricated to test the effect of different device dimensions on maximum achievable deflection as a function of applied current. Actuators can be combined to produce more force and have been integrated with other micromechanical structures. Applications of these actuators include linear and rotating motors, compliant micromechanisms, latches, micro-relays, variable capacitors and tweezers.