UK Parliamentary by-election in Wales
The 1878 Carmarthen Boroughs by-election was a parliamentary by-election held for the House of Commons constituency of Carmarthen Boroughs in West Wales on 11 May 1878.
Vacancy.
The by-election was caused by the resignation of the sitting Liberal MP, Sir Arthur Cowell-Stepney, 2nd Baronet. 
Candidates.
The Liberals selected Benjamin Thomas Williams, QC, a successful barrister and a former Recorder of Carmarthen.
The result.
There being no other candidates putting themselves forward Williams was returned unopposed. 
! scope="col" colspan="2" style="width: 130px"|Party
! scope="col" style="width: 17em"|Candidate
! scope="col" style="width: 5em"|Votes
! scope="col" style="width: 3.5em"|%
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! colspan="3" style="text-align:right;" scope=row | Registered electors
References.
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