A rotary actuator (101) is provided which includes first and second opposing endplates (107); a stator (105) having a first end which is attached to said first endplate, and a second end which is attached to said second endplate; a rotor (103) having first and second eccentrics (125) on a surface thereof; an output attachment ring gear (135) disposed about the periphery of said first and second opposing endplates; a first parallel eccentric gear (131) which is disposed between said first eccentric and said output gear and which meshes with said output gear; a second parallel eccentric gear which is disposed between said second eccentric and said output gear and which meshes with said output gear; a first crosslink (113) which engages said first endplate and said first eccentric gear by way of a first set of surface features (143, 153); and a second crosslink which meshes with said second endplate and said second eccentric gear by way of a second set of surface features. The rotary actuator further includes a star compound gear train which includes a star gear which is in mesh with the output gear across a second mesh, wherein the first mesh is radially separated from the second mesh across an open space.