A rotary electrohydraulic actuator comprising a hydraulic drive unit comprising a first hydraulic motor, a second hydraulic motor that is mounted in tandem with the first hydraulic motor, each hydraulic motor (14, 16) including a hydraulic motor housing having a fluid inlet and a fluid outlet, and a rotor disposed in the hydraulic motor housing so as to rotate about a rotational axis, the rotor including a through opening that is centered on the rotational axis and serves as a hollow output shaft of the hydraulic motor (14, 16), whereby the output shaft provides a gear-free connection to a driven shaft when a driven shaft is disposed in the through opening, wherein the first hydraulic motor and the second hydraulic motor share the same rotational axis; a manifold that defines a fluid path between the fluid inlets and the fluid outlets, the manifold connected to the hydraulic motor housings in such a way as to permit the fluid path to communicate with the fluid inlets and the fluid outlets and the manifold to be spaced apart from the rotational axis; and at least two power plants, each including a hydraulic pump disposed in the fluid path and an electric dual shaft motor that is configured to drive the hydraulic pump, wherein the hydraulic pump comprises a first hydraulic pump and a second hydraulic pump, and the first hydraulic pump is driven by a first shaft of the dual shaft electric motor, and the second hydraulic pump is driven by a second shaft of the dual shaft electric motor, and wherein operation of the electric motor causes the hydraulic pump to supply pressurized fluid to the fluid inlets of the hydraulic motors (14, 16); wherein each power plant is oriented so that the first shaft and the second shaft are non-intersecting with the rotational axis, and each power plant is secured to the manifold such that each fluid inlet of each hydraulic pump (60a, 60b) and each fluid outlet of each hydraulic pump (60a, 60b) communicates with the fluid path, wherein the fluid path passes through each of the first hydraulic motor and the second hydraulic motor, and wherein at least one power plant is mounted on the hydraulic drive unit via the manifold. a hydraulic drive unit comprising a first hydraulic motor, a second hydraulic motor that is mounted in tandem with the first hydraulic motor, each hydraulic motor (14, 16) including a hydraulic motor housing having a fluid inlet and a fluid outlet, and a rotor disposed in the hydraulic motor housing so as to rotate about a rotational axis, the rotor including a through opening that is centered on the rotational axis and serves as a hollow output shaft of the hydraulic motor (14, 16), whereby the output shaft provides a gear-free connection to a driven shaft when a driven shaft is disposed in the through opening, wherein the first hydraulic motor and the second hydraulic motor share the same rotational axis; a manifold that defines a fluid path between the fluid inlets and the fluid outlets, the manifold connected to the hydraulic motor housings in such a way as to permit the fluid path to communicate with the fluid inlets and the fluid outlets and the manifold to be spaced apart from the rotational axis; and at least two power plants, each including a hydraulic pump disposed in the fluid path and an electric dual shaft motor that is configured to drive the hydraulic pump, wherein the hydraulic pump comprises a first hydraulic pump and a second hydraulic pump, and the first hydraulic pump is driven by a first shaft of the dual shaft electric motor, and the second hydraulic pump is driven by a second shaft of the dual shaft electric motor, and wherein operation of the electric motor causes the hydraulic pump to supply pressurized fluid to the fluid inlets of the hydraulic motors (14, 16); wherein each power plant is oriented so that the first shaft and the second shaft are non-intersecting with the rotational axis, and each power plant is secured to the manifold such that each fluid inlet of each hydraulic pump (60a, 60b) and each fluid outlet of each hydraulic pump (60a, 60b) communicates with the fluid path, wherein the fluid path passes through each of the first hydraulic motor and the second hydraulic motor, and wherein at least one power plant is mounted on the hydraulic drive unit via the manifold.