A MEMS actuator (100; 300; 500) comprising a monolithic body (101; 301; 501) of semiconductor material including: a supporting portion (102; 302; 502) of semiconductor material, orientable with respect to a first and a second rotation axis (A, B), the first rotation axis being transverse to the second rotation axis; a first frame (104; 304; 504) of semiconductor material, coupled to the supporting portion through first deformable elements (115; 315; 515) configured to control a rotation of the supporting portion about the first rotation axis; and a second frame (108; 308; 508) of semiconductor material, coupled to the first frame through second deformable elements (116; 316; 516), coupled between the first and the second frames and configured to control a rotation of the supporting portion about the second rotation axis, wherein the first and the second deformable elements carry respective first and second piezoelectric actuation elements (150; 350; 550), characterised in that the first frame (104; 304; 504) has an elongated hexagonal shape which is symmetrical to a first and a second symmetry axis (A, B), the first and second symmetry axes being parallel to the respective first and second rotation axes (A, B), the elongated hexagonal shape having two first sides (104A; 304A; 504A) parallel to the first symmetry axis and four end sides (104B; 304B; 504B), extending parallel two by two and transverse to the first and second symmetry axes (A, B), and the second frame (108; 308; 508) has a regular quadrangular shape which is symmetrical to the first and second symmetry axes and has sides parallel two by two and to the respective end sides of the first frame. a supporting portion (102; 302; 502) of semiconductor material, orientable with respect to a first and a second rotation axis (A, B), the first rotation axis being transverse to the second rotation axis; a first frame (104; 304; 504) of semiconductor material, coupled to the supporting portion through first deformable elements (115; 315; 515) configured to control a rotation of the supporting portion about the first rotation axis; and a second frame (108; 308; 508) of semiconductor material, coupled to the first frame through second deformable elements (116; 316; 516), coupled between the first and the second frames and configured to control a rotation of the supporting portion about the second rotation axis, wherein the first and the second deformable elements carry respective first and second piezoelectric actuation elements (150; 350; 550), characterised in that the first frame (104; 304; 504) has an elongated hexagonal shape which is symmetrical to a first and a second symmetry axis (A, B), the first and second symmetry axes being parallel to the respective first and second rotation axes (A, B), the elongated hexagonal shape having two first sides (104A; 304A; 504A) parallel to the first symmetry axis and four end sides (104B; 304B; 504B), extending parallel two by two and transverse to the first and second symmetry axes (A, B), and the second frame (108; 308; 508) has a regular quadrangular shape which is symmetrical to the first and second symmetry axes and has sides parallel two by two and to the respective end sides of the first frame.