The Duchess of Newcastle or the Duchess of Newcastle-upon-Tyne usually refers to the wife or widow of a Duke of Newcastle. The dukedom became extinct in 1988.
Duchesses of Newcastle-on Tyne and Newcastle
1st creation (1665)
- Margaret Cavendish, Duchess of Newcastle-upon-Tyne (1623–1673) (née Margaret Lucas), English aristocrat, writer and scientist, 2nd wife of William Cavendish, 1st Duke of Newcastle
- Frances Pierrepoint (1630–1695), wife of Henry Cavendish, 2nd Duke of Newcastle
2nd creation (1694)
- Margaret Holles, Duchess of Newcastle-upon-Tyne (1661–1716) (née Margaret Cavendish), wife of John Holles, 1st Duke of Newcastle
3rd creation (1715)
- Harriet Pelham-Holles, Duchess of Newcastle-upon-Tyne (1701–1776) (Lady Harriet Godolphin), wife of Thomas Pelham-Holles, 1st Duke of Newcastle
- Catherine Pelham-Clinton, Countess of Lincoln (1727–1760), wife of Henry Pelham-Clinton, 2nd Duke of Newcastle
- Lady Anna Maria Stanhope, wife of Thomas Pelham-Clinton, 3rd Duke of Newcastle
- Georgiana Mundy (d.1822), wife of Henry Pelham-Clinton, 4th Duke of Newcastle
- Henrietta Hope, wife of Henry Pelham-Clinton, 6th Duke of Newcastle
- Kathleen Pelham-Clinton, Duchess of Newcastle (1872–1955) (née Kathleen Candy), conformation show judge and dog breeder, wife of Henry Pelham-Clinton, 7th Duke of Newcastle
- Olive Muriel Thompson, wife of Francis Pelham-Clinton-Hope, 8th Duke of Newcastle
- Lady Mary Montagu-Stuart-Wortley (1920–1997), 2nd wife of Henry Pelham-Clinton-Hope, 9th Duke of Newcastle
- Sally Ann Wemyss, 3rd wife of Henry Pelham-Clinton-Hope, 9th Duke of Newcastle