| Election Name: | Tamil Nadu assembly by-election, 2016-17 |
| Country: | India |
| Type: | parliamentary |
| Ongoing: | no |
| Previous Election: | 2009 Tamil Nadu assembly by-election |
| Previous Year: | 2009-10 |
| Next Election: | 2019 Tamil Nadu Legislative Assembly by-elections |
| Next Year: | 2019 |
| Election Date: | 19 November 2016 and 21 December 2017 |
| Seats For Election: | vacant seats in the Legislature of Tamil Nadu |
| Image3: | File:Hon CM Photo.jpg |
| Leader3: | M. K. Stalin |
| Party3: | Dravida Munnetra Kazhagam |
| Alliance3: | Secular Progressive Alliance |
| Leaders Seat3: | Kolathur |
| Seats3: | 0 |
| Leader1: | Edappadi K. Palaniswami |
| Leaders Seat1: | Edappadi |
| Party1: | All India Anna Dravida Munnetra Kazhagam |
| Alliance1: | National Democratic Alliance |
| Seats1: | 3 |
| Leader2: | T. T. V. Dhinakaran |
| Leaders Seat2: | Radhakrishnan Nagar |
| Party2: | Independent |
| Seats2: | 1 |
During the 2016–2017 timeframe, by-elections were held in Tamil Nadu, India, due to the following events:
| Date | Event | Independent | Vacant | Total | |||||
|---|---|---|---|---|---|---|---|---|---|
| 19 May 2016 | 2016 Tamil Nadu Legislative Assembly election (Election to Aravakurichi and Thanjavur were cancelled by the EC on confirmed reports of bribing voters) | 134 | 89 | 8 | 1 | 0 | 2 | 232 | |
| 25 May 2016 | Tirupparankundram AIADMK MLA S M Seenivel passes away [1] | 133 | 89 | 8 | 1 | 0 | 3 | 231 | |
| First By-Election (19 November 2016)[2] | 136 | 89 | 8 | 1 | 0 | 0 | 234 | ||
| 6 December 2016 | RK Nagar AIADMK MLA, Tamil Nadu CM J. Jayalalithaa Passes Away[3] | 135 | 89 | 8 | 1 | 0 | 1 | 233 | |
| Disqualification of 18 dissident AIADMK MLAs [4] | 117 | 89 | 8 | 1 | 0 | 19 | 215 | ||
| 24 December 2017 | Second By-Election (21 December 2017)[5] | 117 | 89 | 8 | 1 | 1 | 18 | 216 | |
| 2 August 2018 | Tirupparankundram AIADMK MLA A.K. Bose passes away [6] | 116 | 89 | 8 | 1 | 1 | 19 | 215 | |
| 7 August 2018 | Tiruvarur DMK MLA, Former CM of Tamil Nadu CM M Karunanidhi Passes Away[7] | 116 | 88 | 8 | 1 | 1 | 20 | 214 | |
| 20 February 2019 | Hosur AIADMK MLA P. Balakrishna Reddy convicted by special court[8] | 115 | 88 | 8 | 1 | 1 | 21 | 213 | |
| 21 March 2019 | Sulur AIADMK MLA R Kanagaraj passes away[9] | 114 | 88 | 8 | 1 | 1 | 22 | 212 | |
| 23 May 2019 | Third By-Election (18 April 2019)[10] | 123 | 101 | 8 | 1 | 1 | 0 | 234 | |
| 29 May 2019 | Nanguneri, Congress MLA Vasanthakumar resigned after being elected to Lok Sabha[11] | 123 | 101 | 7 | 1 | 1 | 1 | 233 | |
| 14 June 2019 | Vikravandi DMK MLA K Radhamani passes away | 123 | 100 | 7 | 1 | 1 | 2 | 232 |
The 123 AIADMK members include three independents who contested under the AIADMK symbol. They are M.Thamimun Ansari from Nagapattinam (Manithaneya Jananayaga Katchi), U. Thaniyarasu from Kangayam (Tamil Nadu Kongu Ilaingar Peravai) and Karunas from Tiruvadanai (Mukkulathor Pulipadai).
On 26 October 2016, the Election Commission announced that the election for Thiruparankundram, Aravakurichi and Thanjavur constituencies would be held on 19 November 2016.[12] The outcome was:
| Constituency | Contestant DMK | Contestant ADMK | Winning candidate | Winning party | Margin | |
|---|---|---|---|---|---|---|
| AIADMK | 23,661 | |||||
| Anjugam Boopathy | M. Rangaswamy | AIADMK | 26,874 | |||
| Thiruparankundram | Saravanan | AIADMK | 42,670 |
On 24 November 2017, the Election Commission announced that the election for Radhakrishnan Nagar constituency would be held on 21 December 2017.[13] [14]