Maria was a daughter of wealthy Anglo-Hellenic merchant Demetrios Cassavetti (d.1858) and his wife Euphrosyne (1822–1896) and niece of the Greek Consul and noted patron Alexander Constantine Ionides.

Maria and her cousins Marie Spartali Stillman and Aglaia Coronio were known collectively among friends as "the Three Graces", after the Charites of Greek mythology.

[8] Familiar within the circles of the Pre-Raphaelites for her dark red hair and pale skin, she did her most notable modelling for artist Edward Burne-Jones.

[10] After they broke up, Maria continued to appear in Burne-Jones' paintings as a sorceress or a temptress, such as in his last major work of her, The Beguiling of Merlin (1872–1877), and the controversial Phyllis and Demophoön (1870), which was removed from display at the Royal Watercolour Society.

She died in Paris in 1914 and her body was returned for interment in the family sarcophagus at the Greek Orthodox necropolis of the South Metropolitan Cemetery at Norwood, where she is recorded under her maiden name.