A hydraulic actuator for a combined rear-front braking system of a motorcycle, the actuator comprising: an actuator body having an axially extending through cavity; at least one hydraulic chamber within the actuator body; an inlet duct in fluid communication with the hydraulic chamber, for letting a brake fluid into the hydraulic chamber; a delivery duct in fluid communication with the hydraulic chamber, for sending brake fluid from the hydraulic chamber to a front hydraulic brake of the motorcycle; a tubular piston mounted coaxially slidable in the through cavity of the actuator body, the tubular piston being at least partially inserted into the hydraulic chamber, and having an axially extending through cavity for the passage of a mechanical cable for actuating a rear brake of the motorcycle; wherein the actuator body comprises a main body of overall tubular shape, associated with a complementary body of substantially tubular shape; wherein the hydraulic actuator comprises: an outer portion of the main body; characterised in that the hydraulic actuator further comprises: a radially inner tubular end portion of the main body extending inside the outer portion coaxial with the tubular piston; a transversal wall of the main body connecting the outer portion to the radially inner tubular end portion; wherein the hydraulic chamber is formed between said outer portion, said radially inner tubular end portion and said transversal wall. an actuator body having an axially extending through cavity; at least one hydraulic chamber within the actuator body; an inlet duct in fluid communication with the hydraulic chamber, for letting a brake fluid into the hydraulic chamber; a delivery duct in fluid communication with the hydraulic chamber, for sending brake fluid from the hydraulic chamber to a front hydraulic brake of the motorcycle; a tubular piston mounted coaxially slidable in the through cavity of the actuator body, the tubular piston being at least partially inserted into the hydraulic chamber, and having an axially extending through cavity for the passage of a mechanical cable for actuating a rear brake of the motorcycle; wherein the actuator body comprises a main body of overall tubular shape, associated with a complementary body of substantially tubular shape; wherein the hydraulic actuator comprises: an outer portion of the main body; characterised in that the hydraulic actuator further comprises: a radially inner tubular end portion of the main body extending inside the outer portion coaxial with the tubular piston; a transversal wall of the main body connecting the outer portion to the radially inner tubular end portion; wherein the hydraulic chamber is formed between said outer portion, said radially inner tubular end portion and said transversal wall. an outer portion of the main body; characterised in that the hydraulic actuator further comprises: a radially inner tubular end portion of the main body extending inside the outer portion coaxial with the tubular piston; a transversal wall of the main body connecting the outer portion to the radially inner tubular end portion; wherein the hydraulic chamber is formed between said outer portion, said radially inner tubular end portion and said transversal wall. a radially inner tubular end portion of the main body extending inside the outer portion coaxial with the tubular piston; a transversal wall of the main body connecting the outer portion to the radially inner tubular end portion; wherein the hydraulic chamber is formed between said outer portion, said radially inner tubular end portion and said transversal wall.