Prince Srisiddhi Thongjaya, the Prince Siridhaj Sangkas (; ; 16 October 1857 â 11 March 1910) was a Prince of Siam. As a son of King Mongkut and Chao Chom Manda Bua, he was a member of Siamese royal family.
His mother was a daughter of Chao Phraya Nakhon Noi, a son of King Taksin. He was given full name as Phra Chao Borom Wong Ther Phra Ong Chao Srisiddhi Thongjaya Krom Khun Siridhaj Sangkas ().
He had 4 siblings: 1 elder brother, 1 younger sister, and 2 younger brothers:
He was the minister of Finance from 1894 to 1896.