| Election Name: | 1904 West Monmouthshire |
| Type: | presidential |
| Country: | United Kingdom |
| Previous Election: | West Monmouthshire (UK Parliament constituency)#Elections in the 1900s |
| Previous Year: | 1900 |
| Next Election: | West Monmouthshire (UK Parliament constituency)#Elections in the 1900s |
| Next Year: | 1906 |
| Election Date: | 3 November 1904 |
| Party1: | Liberal-Labour (UK) |
| Popular Vote1: | 7,995 |
| Percentage1: | 70.4 |
| Party2: | Independent politician |
| Popular Vote2: | 3,360 |
| Percentage2: | 29.6 |
| Map Size: | 250px |
| Posttitle: | Subsequent MP |
| Before Party: | Liberal Party (UK) |
| After Party: | Liberal-Labour (UK) |
The 1904 West Monmouthshire by-election was a parliamentary by-election held on 3 November 1904.[1] The constituency returned one Member of Parliament (MP) to the House of Commons of the United Kingdom, elected by the first past the post voting system.
The seat was vacant following the death of the seat's incumbent MP Sir William Vernon Harcourt. Thomas Richards was elected in his place.