The famous King of the Kushan dynasty is Kanishka. The Kushan dynasty was a powerful empire that ruled over parts of Central Asia and northern India from the 1st to the 3rd century CE. Kanishka was one of the most prominent rulers of this dynasty.

Option 1: Kanishka - This is the correct answer.

Option 2: Pulakeshin - This is not the correct answer. Pulakeshin was a ruler of the Chalukya dynasty in South India, not the Kushan dynasty.

Option 3: Harsha - This is not the correct answer. Harsha was a ruler of the Pushyabhuti dynasty in northern India, not the Kushan dynasty.

Option 4: Vikramaditya - This is not the correct answer. Vikramaditya is a legendary king, associated with various dynasties and periods, but not specifically the Kushan dynasty.

Alert - correct answer should be Kanishka.