A high-voltage insulator (100, 101. 102, 150, 200) for securing, as a single insulator or as a component of an insulator stack or string, a high-voltage conductor in an electrical installation or in an electric power line, the insulator comprising an insulating core and a fixing device consisting of a first fastening element and a second fastening element, said fastening elements located at the opposite ends of the insulating core, wherein the first fastening element is configured for connecting, directly or via connecting means, with a high-voltage conductor or with the second fastening element of the preceding high-voltage insulator of said insulator stack or string and the second fastening element is configured for connecting to a support of the power line or to the first fastening element of the subsequent high-voltage insulator of said insulator stack or string, wherein the insulator comprises: a multi-electrode system consisting of m ( m > 5) electrodes mechanically connected with the insulating core and located between ends thereof, the electrodes configured to form, under an impact of a lightning overvoltage, an electric discharge between the first fastening element and an electrode or electrodes adjacent thereto, between adjacent electrodes, and between the second fastening element and an electrode or electrodes adjacent thereto; the insulator is characterized in that it additionally comprises means for compensating the reduction of the insulator creepage distance caused by the multi-electrode system, wherein the electrodes have a T- shaped profile, with a narrow leg, by which each of the electrodes is attached to the insulating core, and with a wide beam that is oriented towards the adjacent electrode, wherein the compensating means are constituted by parts of the insulating core that are enclosed between the legs of the electrodes and by air gaps between the electrodes; and/or the electrodes are embedded in the insulator, wherein the compensating means are formed by a layer of the insulator material separating the electrodes from the insulator surface, and by cuts formed between the adjacent electrodes and reaching the insulator surface. a multi-electrode system consisting of m ( m > 5) electrodes mechanically connected with the insulating core and located between ends thereof, the electrodes configured to form, under an impact of a lightning overvoltage, an electric discharge between the first fastening element and an electrode or electrodes adjacent thereto, between adjacent electrodes, and between the second fastening element and an electrode or electrodes adjacent thereto; the insulator is characterized in that it additionally comprises means for compensating the reduction of the insulator creepage distance caused by the multi-electrode system, wherein the electrodes have a T- shaped profile, with a narrow leg, by which each of the electrodes is attached to the insulating core, and with a wide beam that is oriented towards the adjacent electrode, wherein the compensating means are constituted by parts of the insulating core that are enclosed between the legs of the electrodes and by air gaps between the electrodes; and/or the electrodes are embedded in the insulator, wherein the compensating means are formed by a layer of the insulator material separating the electrodes from the insulator surface, and by cuts formed between the adjacent electrodes and reaching the insulator surface.