Princess Beatrice Bhadrayuvadi (Thai: บีเอตริศภัทรายุวดี; RTGS: Bi-e-trit Phatthrayuwadi; 5 December 1876 – 30 September 1913), was a Princess of Siam (later Thailand).

She was a member of Siamese Royal Family and a daughter of Chulalongkorn, also known as Rama V.[1] Her name was given by her father, King Chulalongkorn, in honour of British Queen Victoria's daughter, The Princess Beatrice.

Her mother was The Noble Consort (Chao Chom Manda) Saeng Kalyanamitra (daughter of Phraya Jayavichit, son of Chao Phraya Nikara Bodindra (To) who built Kalyanamitra Temple.

Princess Beatrice Bhadrayuvadi had 3 full siblings; 2 elder brothers and 1 younger sister; Princess Beatrice listened to Dhamma sermons and wrote down what she remembered so that others could learn from her notes.

[1] Princess Beatrice Bhadrayuvadi died 30 September 1913, aged 36.