Supayalat (Burmese: စုဖုရားလတ်, pronounced: [sṵpʰəjá laʔ]; 13 December 1859 – 24 November 1925) was the last queen of Burma who reigned in Mandalay (1878–1885), born to King Mindon Min and Queen of Alenandaw (literally Middle Palace, also known as Hsinbyumashin or Lady of the White Elephant). The British corruption of her name was "Soup Plate". She was married to her half-brother, Thibaw, who became the last king of the Konbaung dynasty in 1878, upon Mindon Min's death. She is best known for engineering a of 80 to 100 royal family members, to prevent potential rivals from usurping Thibaw's power, although she had always denied any knowledge of the plot, which may have been hatched by her mother together with some of the ministers, including the chancellor Kinwon Min Gyi U Kaung.

Princess Hteik Supayalat aka Princess of Myadaung, with the official title of Siri Suriya Prabha Ratana Devi (သီရိသူရိယပြဘရတနာဒေဝိ), was the second of three daughters born to Mindon and Hsinbyumashin, daughter of Bagyidaw (Mindon's uncle) and Nanmadaw Me Nu born in Pha Lan Gon, and the third of Mindon's four highest-ranking queens. The three other queens of Mindon had no children, and Hsinbyumashin became more powerful after the death of the chief queen Setkya Devi. Thibaw, on the other hand, was the son of a middle-ranking queen, Queen of Laungshe. He was however learned in the Buddhist scriptures and also educated by the missionary Dr. Marks, and became one of Mindon's favourite sons.

In 1878, Thibaw succeeded his father in a bloody succession massacre. Hsinbyumashin, one of Mindon's queens, had grown dominant at the Mandalay court during Mindon's final days. Under the guise that Mindon wanted to bid his children (other princes and princesses) farewell, Hsinbyumashin had all royals of close age (who could potentially be heir to the throne) mercilessly slaughtered by edict, to ensure that Thibaw and her daughter Supayalat would assume the throne.

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