Guildford: Colin Cross, who was elected for the Liberal Democrats in Lovelace ward, has left the party to sit as an Independent councillor.
Gwynedd: Dylan Bullard, who was elected as an Independent candidate in Pwllheli North division, has announced he has joined Plaid Cymru. However he intends to remain in the Independent group on the council.
New vacancies
Haringey: West Green ward, after the resignation of Labour councillor Ishmael Osamor, following a criminal conviction. Term ends 2022.
Middlesbrough: Brambles and Thorntree ward, after the death of Labour councillor Peter Purvis. Term ends May next year.
Oldham: Failsworth East ward, after the resignation of Labour councillor Cheryl Brock. Term ends 2020.
Reigate and Banstead: Kingswood with Burgh Heath ward, after the death of Conservative councillor Ros Mill. Term ends May next year.
South Tyneside: Cleadon and East Boldon ward, after the death of Labour councillor David Townsley. Term ends 2020.
Dates for byelections
Leicester: The byelection due in Belgrave ward will be held on 6 December.
Oldham: The byelection due in Failsworth East ward will be held on 29 November.
Oxford: The byelection due in Wolvercote ward will be held on 6 December.
Surrey: The byelection due in The Byfleets division will be held on 6 December.