Linear actuators (also known as an inchworm actuator) including a magnetically actuatable shape memory alloy (SMA) are described. The linear actuators include a bar and an actuator assembly, configured to achieve a linear displacement of the actuator assembly relative to the bar. A hybrid magnetic trigger including an electromagnet and a permanent magnet is used to selectively attract the magnetically actuatable SMA toward the magnetic trigger. The motion of the magnetically actuatable SMA can be converted to a linear displacement. The magnetically actuatable SMA can be implemented using a SMA exhibiting both ferromagnetic and SMA properties, or by a ferromagnetic mass coupled with an SMA (i.e., a ferromagnetic SMA composite). Linear actuators including bars incorporating a ratchet mechanism, and featureless bars are described. A hydraulic system incorporating actuators including magnetically actuatable SMA membranes is also disclosed.