Hamilton by-election may refer to:
Australia 1934 Hamilton state by-election, NSW Assembly, following the death of Hugh Connell
New Zealand Parliament 1959 Hamilton by-election, following the death of Hilda Ross 2022 Hamilton West by-election, following the resignation of Gaurav Sharma
Scottish Parliament 2025 Hamilton, Larkhall and Stonehouse by-election, following the death of Christina McKelvie
UK Parliament 1943 Hamilton by-election, following the death of Duncan Graham 1945 Hamilton by-election, following the death of Frank Findlay 1967 Hamilton by-election, following the resignation of Tom Fraser 1978 Hamilton by-election, following the death of Alex Wilson 1999 Hamilton South by-election following the appointment of George Robertson as Nato Secretary-General 2023 Rutherglen and Hamilton West by-election, following the recall of Margaret Ferrier