Thomas Southwell, 2nd Viscount Southwell

{{short description|18th-century Irish peer and politician}}

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Thomas Arthur Southwell, 2nd Viscount Southwell (16 April 1742 – 14 February 1796),{{cite web | url = http://www.leighrayment.com/peers/peersS4.htm | archive-url = https://web.archive.org/web/20080608023745/http://www.leighrayment.com/peers/peersS4.htm | archive-date = 8 June 2008 | title = Leigh Rayment - Peerage | url-status = usurped | accessdate = 12 June 2009 }} styled The Honourable from 1766 until 1780, was an Irish peer and politician.

He was the oldest son of Thomas Southwell, 1st Viscount Southwell and his wife Margaret Hamilton, daughter of Arthur Cecil Hamilton of Castle Hamilton, Killeshandra Co. Cavan.{{cite book | last = Debrett | first = John | publisher = G. Woodfall | edition = 17th | title = Debrett's Peerage of the United Kingdom of Great Britain and Ireland | volume = II | year = 1828 | location = London | pages = 781 }} His younger brother was Robert Henry Southwell.{{cite book | last = Lodge | first = John | editor = Mervyn Archdall | title = The Peerage of Ireland or A Genealogical History of the Present Nobility of that Kingdom | volume = I | location = Dublin | publisher = James Moore | year = 1789 | pages = 27–28 }} Southwell was educated at Trinity College Dublin.{{cite web | url = http://thepeerage.com/p6118.htm#i61179 | title = ThePeerage - Thomas Arthur Southwell, 2nd Viscount Southwell of Castle Mattress | accessdate = 12 June 2009 }} In 1780, he succeeded his father as viscount.

In 1767, Southwell entered the Irish House of Commons for County Limerick, the same constituency his father had represented before, and sat for it until the following year.{{cite web | url = http://www.leighrayment.com/commons/irelandcommons.htm | archive-url = https://web.archive.org/web/20080607022535/http://www.leighrayment.com/commons/irelandcommons.htm | archive-date = 7 June 2008 | title = Leigh Rayment - Irish House of Commons 1692-1800 | url-status = usurped | accessdate = 12 June 2009 }}