Isa or Isabella Jane Blagden (30 June 1816 or 1817 – 20 January 1873) was an English-language novelist and poet born in the East Indies or India, who spent much of her life among the English community in Florence. She was notably friendly with the Browning, Bulwer-Lytton and Trollope families.
Blagden's father's first name is given as Thomas in the records of the Florentine Protestant cemetery and her nationality as Swiss, but she was widely thought to be the illegitimate offspring of an English father and an Indian mother. This seemed to be confirmed by an Oriental appearance. There is circumstantial evidence that she was born in Calcutta, the natural daughter of one Thomas Bracken and of a Eurasian, possibly named Blagden. Little is known firmly about her before she arrived in 1850 in Florence, where she soon became a feature of the English community. She was probably educated at Louisa Agassiz's Ladies School near Regent's Park, London, which was favoured by English parents in India.
In Florence Blagden had a comfortable income (possibly an allowance from her father and later his estate) and was remembered as a kind, generous friend, notably to the Browning, Bulwer-Lytton and Trollope families. She is said to have occupied "a unique place in the Brownings' circle by virtue of her intimacy with both poets." She may have been romantically involved with Robert Bulwer-Lytton, the poet son of the novelists Edward Bulwer-Lytton and his wife Rosina, after nursing him in 1857.
Blagden's earliest pieces were two poems inspired by work by Edward Bulwer-Lytton, which appeared in The Metropolitan Magazine in July 1842 and April 1843. Another, entitled "To George Sand on her Interview with Elizabeth Barrett Browning", commemorated a meeting between the two writers in 1852.