Ada Leverson was a British writer who is now known primarily for her work as a novelist.

She began writing during the 1890s, as a contributor to Black and White, Punch, and The Yellow Book. She was a loyal friend to Oscar Wilde, who called her Sphinx. She was a wit, and a friend of Max Beerbohm; her writing has been compared to Beerbohm's, and the stories of Saki.

She was also a friend of George Moore; Osbert Sitwell in Great Morning has an anecdote in which she tries, unsuccessfully, to get Moore to see the young William Walton. Of the Sitwells' circle - Sacheverall Sitwell dedicated a poetry collection to her, while she was hopelessly in love with Osbert - she lived out her old age in the Hotel Porta Rossa in Florence.