| Prabai Bannabilas | |
| Full Name: | Prabai Bannabilas |
| House: | Chakri Dynasty |
| Mother: | Chao Chom Manda Phrom |
| Birth Date: | 13 August 1885 |
| Birth Place: | Grand Palace Bangkok, Siam |
| Death Place: | Bangkok, Siam |
Princess Prabai Bannabilas (Thai: ประไพพรรณพิลาศ; ; 13 August 1885 - 17 September 1886) was the Princess of Siam (later Thailand). She was a member of the Siamese Royal Family. She was a daughter of Chulalongkorn, King Rama V of Siam.
Her mother was Chao Chom Manda Phrom (daughter of Phraya Phitsanuloka Thibodi). She had 3 siblings, 1 elder sister, 1 younger brother and 1 younger sister:
Princess Prabha Bannabilaya and Princess Prabai Bannabilas were the only set of twins of King Chulalongkorn, and they were the fourth set of twins in Chakri Dynasty. The three previous set of twins were:
Princess Prabai Bannabilas suffered from a terrible illness and died on 17 September 1886, at the age of 1 year and 1 month. The Royal Crematorium was created in Wat Ratchabophit by her uncle Prince Bhanurangsi Savangwongse, the Prince Bhanubhandhubongse Voradej, and the cremation ceremony was performed by her father, King Chulalongkorn on 29 December 1886.
| Princess Prabai Bannabilas | Father: Chulalongkorn, King Rama V of Siam | Paternal Grandfather: Mongkut, King Rama IV of Siam | Paternal Great-grandfather: Buddha Loetla Nabhalai, King Rama II of Siam |
| Paternal Great-grandmother: Queen Sri Suriyendra | |||
| Paternal Grandmother: Queen Debsirindra | Paternal Great-grandfather: Prince Sirivongse, the Prince Matayabidaksa | ||
| Paternal Great-grandmother: Mom Noi Sirivongs na Ayudhya | |||
| Mother: Chao Chom Manda Phrom | Maternal Grandfather: Phraya Phitsanuloka Thibodi | Maternal Great-grandfather: unknown | |
| Maternal Great-grandmother: unknown | |||
| Maternal Grandmother: unknown | Maternal Great-grandfother: unknown | ||
| Maternal Great-grandmother: unknown |