List of New South Wales Legislative Council by-elections (1845–1856)

Between 1843 and 1856 the New South Wales Legislative Council was a hybrid in which some members of the Council were elected and the balance were appointed by the Governor. A by-election was held for the when an elected member's seat became vacant through resignation, death or some other reason. In 1856 the unicameral Legislative Council was abolished and replaced with an elected Legislative Assembly and an appointed Legislative Council.

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1843–1848
! District ! Incumbent ! Reason ! Date ! Winner
 * - bgcolor="#cccccc"
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 * Town of Melbourne
 * Henry Condell
 * Resignation
 * 14 March 1844
 * Joseph Robinson
 * Port Phillip
 * Charles Ebden & Alexander Thomson
 * Resignations
 * 23 April 1844
 * Adolphus Young & Sir Thomas Mitchell
 * Port Phillip
 * Sir Thomas Mitchell
 * Resignation.
 * 17 September 1844
 * Benjamin Boyd
 * County of Camden
 * Roger Therry
 * Resigned, appointed to the Supreme Court (Port Phillip).
 * 27 February 1845
 * John Benton Wild
 * Counties of St Vincent and Auckland
 * John Coghill
 * Resigned to travel to England.
 * 19 April 1845
 * Robert Lowe
 * Port Phillip
 * Thomas Walker
 * Resignation
 * 7 August 1845
 * Maurice O'Connell Jr.
 * Port Phillip
 * Adolphus Young
 * Resignation
 * 7 August 1845
 * Thomas Boyd
 * Northumberland Boroughs
 * D'Arcy Wentworth
 * Resigned
 * 16 September 1845
 * Patrick Grant
 * Port Phillip
 * Benjamin Boyd
 * Resignation
 * 26 September 1845
 * Edward Curr
 * Northumberland Boroughs
 * Patrick Grant
 * Election void (property qualification)
 * 22 November 1845
 * Patrick Grant
 * County of Northumberland
 * William Foster
 * Resigned
 * 27 October 1845
 * Henry Dangar
 * Port Phillip
 * Thomas Boyd
 * Resignation
 * 23 January 1846
 * Edward Brewster
 * Port Phillip
 * Edward Curr
 * Resignation
 * 29 June 1846
 * John Foster
 * County of Argyle
 * William Bradley
 * Resigned
 * 24 July 1846
 * William Faithfull
 * Port Phillip
 * John Lang
 * Vacated by absence
 * 22 December 1847
 * John Airey
 * County of Durham
 * Richard Windeyer
 * Died in December 1847.
 * 19 February 1848
 * Stuart Donaldson
 * Port Phillip
 * Edward Brewster
 * Resignation
 * 15 March 1848
 * Charles Ebden
 * colspan="5" |
 * John Lang
 * Vacated by absence
 * 22 December 1847
 * John Airey
 * County of Durham
 * Richard Windeyer
 * Died in December 1847.
 * 19 February 1848
 * Stuart Donaldson
 * Port Phillip
 * Edward Brewster
 * Resignation
 * 15 March 1848
 * Charles Ebden
 * colspan="5" |
 * Charles Ebden
 * colspan="5" |
 * colspan="5" |

1848–1851
! By-election ! Incumbent ! Reason ! Date ! Winner
 * - bgcolor="#cccccc"
 * - bgcolor="#cccccc"
 * Port Phillip
 * James Williamson
 * Resigned
 * 27 February 1849
 * William Macarthur
 * County of Cumberland
 * Nelson Lawson
 * Died February 1849.
 * March 1849
 * Robert Fitzgerald
 * Counties of St Vincent and Auckland
 * George Hill
 * Resigned
 * 20 June 1849
 * Daniel Cooper
 * Counties of Cook and Westmoreland
 * James Martin
 * Election void (property qualification)
 * 20 June 1849
 * James Martin
 * Port Phillip
 * Edward Curr
 * Resigned
 * 23 June 1849
 * John Foster
 * County of Durham
 * Stuart Donaldson
 * Election void.
 * 25 June 1849
 * Stuart Donaldson
 * Port Phillip
 * James Palmer
 * Resigned
 * 17 July 1849
 * Henry Moor
 * City of Sydney
 * Robert Lowe
 * Resigned
 * 18 December 1849
 * William Bland
 * County of Cumberland
 * Charles Cowper
 * Resigned
 * 13 March 1850
 * James Byrnes
 * Port Phillip
 * John Foster & Lauchlan Mackinnon
 * Resigned
 * 11 June 1850
 * Charles Ebden & William Mercer
 * City of Sydney
 * William Bland
 * Resigned
 * 24 July 1850
 * John Lang
 * Counties of Gloucester, Macquarie, and Stanley
 * Kenneth Snodgrass
 * Resigned
 * 25 October 1850
 * Richard Jones
 * Town of Melbourne
 * Earl Grey
 * Vacated by absence
 * 7 November 1850
 * William Westgarth
 * colspan="5" |
 * Counties of Gloucester, Macquarie, and Stanley
 * Kenneth Snodgrass
 * Resigned
 * 25 October 1850
 * Richard Jones
 * Town of Melbourne
 * Earl Grey
 * Vacated by absence
 * 7 November 1850
 * William Westgarth
 * colspan="5" |
 * William Westgarth
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1851–1856
! By-election ! Incumbent ! Reason ! Date ! Winner
 * - bgcolor="#cccccc"
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 * City of Sydney
 * John Lang
 * Resigned
 * 18 November 1851
 * Robert Campbell
 * Stanley Boroughs
 * Richard Jones
 * Died in November 1852.
 * January 1853
 * Henry Russell
 * County of Durham
 * Stuart Donaldson
 * Resigned
 * 28 February 1853
 * Alexander Park
 * Pastoral Districts of Moreton, Wide Bay, Burnett, and Maranoa
 * Francis Bigge
 * Resigned
 * 3 March 1853
 * Richard Smith
 * City of Sydney
 * John Lamb
 * Resigned
 * 10 March 1853
 * William Thurlow
 * Cumberland Boroughs
 * John Holden
 * Resigned
 * 22 April 1853
 * William Bowman
 * Pastoral Districts of Wellington and Bligh
 * James Bettington
 * Resigned
 * 27 April 1853
 * Charles Finch
 * Pastoral District of Maneroo
 * Arthur Jeffreys
 * Resigned
 * 19 April 1854
 * Daniel Egan
 * County of Stanley
 * John Richardson
 * Resigned
 * 28 April and 23 May 1854
 * Arthur Hodgson
 * City of Sydney
 * William Wentworth
 * Resigned
 * 2 May 1854
 * Henry Parkes
 * County of Stanley
 * Arthur Hodgson
 * Election void
 * 10 August 1854
 * John Lang
 * Roxburgh and Wellington
 * William Suttor Sr.
 * Resigned
 * 23 October 1854
 * Saul Samuel
 * City of Sydney
 * William Thurlow
 * Resigned
 * 24 January 1855
 * James Wilshire
 * Sydney Hamlets
 * Thomas Smart
 * Resigned to travel to England
 * 21 February 1855
 * Stuart Donaldson
 * Pastoral Districts of Lachlan and Lower Darling
 * William Macarthur
 * Resigned
 * 2 March 1855
 * William Macleay
 * Counties of Murray and St Vincent
 * Alick Osborne
 * Resigned
 * 19 March 1855
 * Daniel Cooper
 * Clarence and Darling Downs
 * George Leslie
 * Resigned
 * 21 April 1855
 * Thomas Hood
 * Pastoral Districts of New England and Macleay
 * Matthew Marsh
 * Resigned to return to England
 * 26 April 1855
 * Robert Massie
 * Pastoral Districts of New England and Macleay
 * Robert Massie
 * Election void
 * 27 August 1855
 * Thomas Rusden
 * Stanley Boroughs
 * Henry Russell
 * Resigned
 * 10 September 1855
 * John Richardson
 * }
 * Thomas Hood
 * Pastoral Districts of New England and Macleay
 * Matthew Marsh
 * Resigned to return to England
 * 26 April 1855
 * Robert Massie
 * Pastoral Districts of New England and Macleay
 * Robert Massie
 * Election void
 * 27 August 1855
 * Thomas Rusden
 * Stanley Boroughs
 * Henry Russell
 * Resigned
 * 10 September 1855
 * John Richardson
 * }
 * 10 September 1855
 * John Richardson
 * }
 * }