The 1886 County Carlow by-election was a parliamentary by-election held for the United Kingdom House of Commons constituency of County Carlow on 29 January 1886.[1] The sitting member, Edmund Dwyer Gray had been re-elected in the general election of 1885, but having run and been elected also in the new constituency of Dublin St Stephen's Green, he chose to sit for the latter.[2] The County Carlow seat thus became vacant, and in the ensuing by-election, another Irish Nationalist candidate, John Aloysius Blake, was elected unopposed.[3]