Sultan Ismail Petra ibni Almarhum Sultan Yahya Petra was the 28th Sultan of Kelantan and the 11th Sultan of Modern Kelantan who reigned from 30 March 1979 to 13 September 2010. He succeeded on the death of his father, Sultan Yahya Petra. He was succeeded by his eldest son, Sultan Muhammad V who ascended the throne on 13 September 2010 after being deemed incapacitated. Sultan Ismail Petra died at the Raja Perempuan Zainab II Hospital in Kota Bharu on 28 September 2019, aged 69, after 10 years of suffering from a massive stroke and was buried at the Kelantan Royal Mausoleum.

Kelantan Royal Mausoleum or Langgar Royal Mausoleum is a Kelantan royal burial ground located at Kampung Langgar near Kota Bharu, Kelantan, Malaysia.