Katherine Austen (1629 – ca. 1683) was a British diarist and poet best known for Book M, her manuscript collection of meditations, journal entries, and verse.
Austen was born in London, one of seven children, to Katherine Wilson (d. 1648) and her husband Robert (d. 1639), a draper. She married Thomas Austen (1622–1658), a barrister, in 1645. After his death at the age of 36, she entered into an involved legal battle with his family in order to retain his manor in Middlesex for her three children, Thomas, Robert, and Anne.
Her manuscript of 114 folios, Book M (BL, Add. MS 4454), was written over six or seven years during her period of mourning — her Most saddest Yeares (60r) — and includes material on her lawsuit, interpretations of dreams (her own and others), historical commentary, prayers, letters, financial materials, and 34 verse meditations in rhyming couplets.
One of her best known poems from the book is the estate poem On the Situation of Highbury. This poem demonstrates her familiarity with the genre, although her poem is unusual in leaving the estate's dweller anonymous. The book also contains an essay on Saint Hildegard of Bingen.
She declined to remarry, citing her regard for her late husband and her fears for the financial interests of her children. Under the doctrine of coverture she retained her widow's status as an independent legal entity if she did not remarry. Although she did not marry she had a suitor, the Scottish doctor Alexander Callendar.
She lived in Hoxton until she died. The date of her death is unknown but it happened in 1683.