A rotor (3, 3', 3"') for a hover-capable aircraft, comprising: - a hub rotatable about a first axis and, in turn, comprising a plurality of blades; - a mast connectable to a drive member of said aircraft and operatively connected to said hub to drive the hub in rotation about said first axis; damping means (15; 20a, 20b; 21a, 21b) to dampen the transmission of vibrations to said mast in a plane orthogonal to said first axis; said damping means (15; 20a, 20b; 21a, 21b) in turn comprising at least one first mass (20a, 20b) and at least one second mass (21a, 21b) that can eccentrically rotate about said first axis, respectively with a first and a second speed of rotation ((N-1) ∗ Q; - (N+1) ∗ Q) with respect to said mast; said first mass (20a, 20b) and second mass (21a, 21b) being operatively connected to said mast to generate, respectively, a first and a second damping force on said mast having a main component in a direction radial to said first axis; said rotor (3, 3', 3"') further comprising a transmission unit (19, 19', 19"'), which is functionally interposed between said mast and said first and second masses (20a, 20b; 21a, 21b) so as to drive said first and second masses (20a, 20b; 21a, 21b) in rotation in opposite directions to each other; wherein said first and second masses (20a, 20b; 21a, 21b) generate, in use, a resultant force with a sinusoidal course on said mast; said rotor (3, 3', 3"') further comprising actuator means (80a, 80b, 81a, 81b) selectively operable to vary the amplitude and phase of said resultant force; said actuator means (80a, 80b, 81a, 81b) comprising: - a drive member; - a support element operatively connected to one of said first and second masses (20a, 20b; 21a, 21b) and rotatable with respect to said mast; and - a further transmission unit (65, 67) that can be driven by said drive member and designed to drive, in use, said support element; characterized in that said further transmission unit (65, 67) being configured so as to irreversibly transmit motion only from an output member of said drive member to said support element and to prevent the transmission of motion in the opposite direction from said support element to said drive member; said further transmission unit (65, 67) comprising a worm screw that can be operated by said drive member, and helical gear teeth carried by said support element and irreversibly meshing with said worm screw; said rotor (3, 3', 3"') comprising, for each said first mass (20a, 20b) and second mass (21a, 21b), an associated casing (62, 63); said associated casing (62, 63) rotating integrally with said mast and with said drive member about said first axis, and at least partly housing said further transmission unit (66, 67); the associated output member rotating with respect to said casing (62, 63) about a second axis transversal to said first axis; said support element being mounted in a manner angularly integral with said casing (62, 63) about said first axis. - a hub rotatable about a first axis and, in turn, comprising a plurality of blades; - a mast connectable to a drive member of said aircraft and operatively connected to said hub to drive the hub in rotation about said first axis; - a drive member; - a support element operatively connected to one of said first and second masses (20a, 20b; 21a, 21b) and rotatable with respect to said mast; and - a further transmission unit (65, 67) that can be driven by said drive member and designed to drive, in use, said support element;