Nang Keo Phimpha (1343–1438), an epithet meaning literally "The Cruel", was Queen of Lan Xang in 1438, taking the regnal name Samdach Brhat-Anya Sadu Chao Nying Kaeva Bhima Fa Mahadevi. She is also known by her title Maha Devi, and may have been the only reigning female sovereign of the kingdom of Lan Xang. According to some chronicles, she briefly occupied the throne for a few months, before she was deposed and killed at ninety-five years old. Her brief reign was the culmination of a ten-year period of regicide, which she orchestrated through a series of puppet kings.
The true identity of the Maha Devi is a matter of dispute both in the chronicles of later periods, and among current scholars. She has variously been described as the eldest daughter, younger sister, principal wife, or step-mother of Samsenthai. Of the few solid clues to her identity, her title as Maha Devi or "Great Goddess," was reserved for only the senior queen of a ruling monarch. Scholars including Martin Stuart-Fox and Amphay Dore, point out that both her age at the time of execution and title as Maha Devi indicate her true identity to be Keo Lot Fa the Queen Consort of Fa Ngum from Ayutthaya who would have assumed the title of Maha Devi after the death of Queen Keo Kang Nya in 1368, shortly before Fa Ngum was deposed in 1371. Although her identity remains a mystery, the consensus among the royal chronicles remains that she was the de facto ruler during a brutal succession dispute between court factions from the death of Lan Kham Deng to the accession of Chakkaphat Phaen Phaeo.