A geared rotary actuator including first and second adjacent, axially aligned actuator slices, each slice having an epicyclic-type reduction gear train including a rotatable input sun gear, a planetary gear assembly driven by the sun gear, and first and second output ring gears driven by the planetary gears, the second output ring gear of each slice being an earth ring gear in use, and the two adjacent earth ring gears being interconnected by axially extending clip means limiting the amount by which said adjacent earth ring gears can be displaced from one another in an axial direction while permitting limited tilting movement of one of the earth ring gears relative to the other to accommodate flexure of the actuator about its longitudinal axis in use.