East Londonderry was the only constituency to elect an independent unionist MLA in 2011, and his death in office means the outcome of the latest vote looks unpredictable.
David McClarty had been deselected by the UUP in 2010 but decided to fight for the seat alone the following year – and won.
Highly-respected as a unionist moderate, he succumbed to cancer in 2014 and his seat was taken by his assistant, Claire Sugden.
However, Mr McClarty’s victory as an independent had come against the backdrop of a political career dating back to the 1980s, and it remains to be seen if Ms Sugden (who is 29, and has never been elected) has sufficient pull with the voters to retain her seat.
Besides Ms Sugden, the DUP had held three seats in the constituency, and the SDLP and Sinn Fein one each.
The UUP is running two of its Causeway Coast and Glens councillors in the area, and will be hoping to capitalise on the absence of the candidate who has been the overwhelming ballot box favourite in the previous three Assembly elections – the DUP’s Gregory Campbell MP.
Along with Sammy Wilson MP in East Antrim, he was forced to relinquish his MLA’s seat in a clampdown on ‘double-jobbing’.
The unionist scramble for seats could leave either the TUV or UKIP with a chance to edge into a seat.
However, both parties are fielding fairly inexperienced, unelected figures for the seats (and the latter party had not stood at all in the region in either the 2015 General Election or the 2011 council one);
Adding to the mix further is Russell Watton of the UVF-linked PUP.
In the Coleraine district in the 2014 council elections, Mr Watton topped the poll with 777 first-preference votes, beating nearest unionist rival George Duddy of the DUP by 67 votes (and Stephanie Quigley of the SDLP by 56 votes).
His candidacy could prove significant on the day, in what one unionist candidate predicted will be “a fight to the finish”.
Caoimhe Archibald (SF)
Jordan Armstrong (TUV)
Yvonne Boyle (Alliance)
Maurice Bradley (DUP)
Aaron Callan (UUP)
Stuart Canning (Cons.)
Tor Christie (Ind.)
Amber Hamill (Green)
David Harding (Cons.)
William McCandless (UUP)
Adrian McQuillan (DUP)
Gerry Mullan (SDLP)
Cathal óhOisín (SF)
Steven Parkhill (UKIP)
George Robinson (DUP)
Claire Sugden (Ind.)
Russell Watton (PUP)
RESULTS OF 2011 ELECTION:
Gregory Campbell (DUP) 6,319 (18.2%)
Cathal O hOisin (SF) 4,681 (13.5%)
George Robinson (DUP) 3,855 (11.1%)
David McClarty (Ind.) 3,003 (8.6%)
John Dallat (SDLP) 2,967 (8.5%)
Bernadette Archibald (SF) 2,639 (7.6%)
Adrian McQuillan (DUP) 2,633 (7.6%)
Thomas Conway (SDLP) 2,222 (6.4%)
Barney Fitzpatrick (Alliance) 1,905 (5.5%)
Boyd Douglas (TUV) 1,568 (4.5%)
Lesley Macaulay (UUP) 1,472 (4.2%)
David Harding (UUP) 1,458 (4.2%)