School closure plans in Gwynedd have proved a contentious issue
Llais Gwynedd, which was originally set up to campaign against rural school closures, has taken another seat in a by-election on Gwynedd council.
The group's David Lloyd Hughes won a seat from Labour in the Bowydd and Rhiw ward.
Plaid Cymru remains in minority control of the 75-member council, while Llais Gwynedd is the third largest group.
Meanwhile, Liberal Democrats and Labour retained three seats each in Newport council by-elections.
The by-elections were caused by the deaths of councillors during the campaign for the May elections.
In Gwynedd, Bowydd and Rhiw seat was contested following the death of the previous Labour councillor during the campaign.
There are 35 Plaid seats in Gwynedd, along with 18 independents, 13 Llais Gwynedd, four Labour and five Liberal Democrats.
The Labour councillors elected in Newport's Bettws ward were Val Delahaye, Glyn Jarvis and Noel Francis Trigghold.
The new Lib Dem councillors in the St Julians ward are Gill Ford, Carmel Townsend and Ed Townsend.
There is still no agreement who will run the council after the May election and coalition negotiations continue.
In Newport two councillors died just before the elections in the two wards, but it meant the vote in all the ward's seats had to be delayed.
The city was a Labour authority before the elections. There are 50 seats, and it now has a political make-up of 22 Labour councillors, 17 Conservatives, nine Liberal Democrats, one Plaid Cymru and one independent.