| Country: | Northern Territory |
| Type: | parliamentary |
| Ongoing: | no |
| Election Date: | 7 December 1991 |
| Party1: | Australian Labor Party (Northern Territory Branch) |
| Popular Vote1: | 1,256 |
| Percentage1: | 51.1% |
| Swing1: | 5.6 |
| Candidate2: | Janice Collins |
| Party2: | Country Liberal Party |
| Popular Vote2: | 561 |
| Percentage2: | 22.7% |
| Swing2: | 20.6 |
| Candidate4: | Colin Firmin |
| Party4: | Independent politician |
| Popular Vote4: | 361 |
| Percentage4: | 14.6% |
| Swing4: | 14.6 |
| Candidate5: | Peter Byrnes |
| Party5: | Independent politician |
| Popular Vote5: | 288 |
| Percentage5: | 11.6 |
| Swing5: | 11.6 |
| MP | |
| Before Party: | Australian Labor Party (Northern Territory Branch) |
| After Party: | Australian Labor Party (Northern Territory Branch) |
A by-election for the seat of Millner in the Northern Territory Legislative Assembly was held on 7 December 1991. The by-election was triggered by the resignation of Labor member and Leader of the Opposition Terry Smith. The seat had been held by Smith since a previous by-election in 1981.