Maria Stella Wynn, Lady Newborough (later Baroness Ungern-Sternberg; née Chiappini; 16 April 1773 – 23 December 1843) was an Italian-born memoirist, the self-styled legitimate daughter of Louis Philippe II, Duke of Orléans.

In 1830 she published her proofs under the title Maria Stella ou un échange d'une demoiselle du plus haut rang contre un garçon de plus vile condition (reprinted 1839 and 1849).

He for his part treated the whole thing with amused contempt, and Baroness Newborough-Sternburg de Joinville, or Marie Étoile d'Orléans, as she called herself, was suffered to live in Paris until on 23 December 1843 she died in poverty and obscurity.

Vitrac identifies the real father of Maria Stella with Count Carlo Battaglini of Rimini, who died in 1796 without issue; the case being not one of substitution, but of ordinary farming out to avoid a scandal.

In 2017 the city council of Modigliana set up a programme of events to commemorate the figure of Maria Stella, including conferences, lectures, studies and a theatre historical drama written and directed by L.A. Mazzoni and played by actors of Filodrammatica Berton.