The 1916 South Londonderry by-election was held on 22 May 1916. The by-election was held due to the resignation of the incumbent Irish Unionist MP, John Gordon. It was won by the Irish Unionist candidate Denis Henry[1] (a Catholic).
It was the first by-election to be held in Ireland after the Easter rebellion, and the rebellion had had no discernible impact on the contest.
| Party | Candidate | Votes | % | ±% | |
|---|---|---|---|---|---|
| Irish Unionist | Denis Henry | 3,808 | 94.7 | +42.4 | |
| Ind. Unionist | Arthur Turnbull | 214 | 5.3 | New | |
| Majority | 3,594 | 89.4 | +85.0 | ||
| Turnout | 4,022 | 47.8 | −43.6 | ||
| Registered electors | 8,416 | ||||
| Irish Unionist hold | Swing | ||||