| Election Name: | 1913 Grey by-election |
| Country: | New Zealand |
| Flag Year: | 1913 |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1911 New Zealand general election |
| Previous Year: | 1911 general |
| Next Election: | 1914 New Zealand general election |
| Next Year: | 1914 general |
| Election Date: | (first round) (second round) |
| Candidate1: | Paddy Webb |
| Party1: | Social Democratic Party (New Zealand) |
| Popular Vote1: | 3,477 |
| Percentage1: | 55.30 |
| Candidate2: | Henry Michel |
| Party2: | Reform Party (New Zealand) |
| Popular Vote2: | 2,811 |
| Percentage2: | 44.70 |
| Member | |
| Before Election: | Arthur Guinness |
| After Election: | Paddy Webb |
| Before Party: | New Zealand Liberal Party |
| After Party: | Social Democratic Party (New Zealand) |
The Grey by-election of 1913 was a by-election held for during the 18th New Zealand Parliament. As no candidate won an absolute majority on the first ballot on 17 July, a second round was held on 24 July.[1] The seat had become vacant due to the death of Arthur Guinness. Three candidates contested the seat, and it was won by the left-wing candidate, who was elected on the second ballot with Liberal support.
The following tables give the election results: