Maha Chakkraphat (Thai: มหาจักรพรรดิ, literally translated as The Great Emperor) was king of the Ayutthaya kingdom from 1548 to 1564 and 1568 to 1569. Originally called Prince Thianracha, or Prince Tien, he was put on the throne by Khun Phiren Thorathep and his supporters of the Sukhothai clan, who had staged a coup by killing the usurper King Worawongsathirat and Sudachan.
Prince Thianracha (พระเฑียรราชา) was a son of Ramathibodi II. His half-brother Prince Chairachathirat, which had been crowned King of Ayutthaya in 1534, elevated Thianracha to Uparaja, but did not confer on him the title of King of Sukhothai. Thianracha joined his brother in the campaigns against Lanna and, in 1546, led the siege of Chiang Mai.
Chairacha died in 1546 and his son (and Thianracha's nephew) Phra Kaewfa succeeded to the throne as King Yodfa, with his mother Si Suda Chan as regent. She had Yodfa killed in 1548 and eventually put her paramour on the throne as Khun Worawongsathirat. Before doing so however, Thianracha was her co-regent, but wishing to remain faithful to his wife Sri Suriyothai, he became a monk to the Queen Mother's amorous advances.
"A band of brothers", retired officers, led by Khun Piren staged a counter-coup, killing Worawongsathirat and Si Suda Chan. Phiren Thorathep then elevated Prince Thianracha to the throne as Phra Maha Chakkraphat.