Viscount Marchwood, of Penang and of Marchwood in the County of Southampton, is a title in the Peerage of the United Kingdom. It was created in 1945 for the businessman and Conservative politician Frederick Penny, 1st Baron Marchwood. He had already been created a Baronet, of Marchwood in the County of Southampton, in the Baronetage of the United Kingdom on 19 June 1933, and Baron Marchwood, of Penang and of Marchwood in the County of Southampton, in 1937, also in the Peerage of the United Kingdom.
As of 2017[update] the titles are held by his grandson, the third Viscount, who succeeded his father in 1979. The third Viscount was educated at Winchester College and served in the Royal Horse Guards, before a career in the drinks industry, first at Cadbury Schweppes, then as managing director of Moet et Chandon. 
Viscounts Marchwood (1945)
- Frederick George Penny, 1st Viscount Marchwood (1876–1955)
- Peter George Penny, 2nd Viscount Marchwood (1912–1979)
- David George Staveley Penny, 3rd Viscount Marchwood (b. 1936)
The heir apparent is the present holder's son the Hon. Peter George Worsley Penny (b. 1965)
The heir apparent's heir apparent is his son Christopher (Kit) David George Penny (b. 1999)
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- "David George Staveley Penny, 3rd Viscount Marchwood". thePeerage.com.
- Kidd, Charles, Williamson, David (editors). Debrett's Peerage and Baronetage (1990 edition). New York: St Martin's Press, 1990,[page needed]
- Leigh Rayment's Peerage Pages [self-published source][better source needed]