3rd December 2015 (5)
10th December 2015 (7)
15th / 16th / 17th December 2015 (6)
23rd December 2015 (1)
There were 19 by-elections for 20 seats during December with 3 (15%)changing hands. The results, based on the No Description in East Herts, Hertford Heath being a Conservative whilst the one in Ryedale, Derwent a Liberal Democrat, can be summarised by:
| Party | Candidates | Defended | Retained | Gained | Lost | Won | retention rate |
| Conservative | 20 | 13 | 12 | 1 | 1 | 13 | 92% |
| Labour | 18 | 4 | 4 | 4 | 100% | ||
| Liberal Democrat | 15 | 1 | 1 | 1 | 2 | 100% | |
| UKIP | 15 | 1 | 1 | 0% | |||
| Green | 9 | ||||||
| SNP | 1 | ||||||
| Plaid Cymru | 1 | ||||||
| Independent | 5 | ||||||
| Bournemouth Independent | 2 | ||||||
| Guildford Greenbelt Group | 1 | ||||||
| Health Concern | 1 | 1 | 1 | 0% | |||
| Liberal | 1 | 1 | 1 | ||||
| Patria | 1 | ||||||
| Socialist | 1 | ||||||
| Yorkshire First | 1 | ||||||
| Total | 92 | 20 | 17 | 3 | 3 | 20 | 85% |
Conservatives gained Worcestershire: Stourport-on-Severn from Health Concern on a swing of 5.1% since a 2013 by-election, ~4% since May 2013 and ~5½% since 2009
- a 2 member Division returning 1 Health Concern / 1 Conservative in 2005, 2 Health Concern in 2009 and 1 UKIP / 1 Health Concern in 2013
- the UKIP Councillor resigned shortly after being elected and was replaced by the former Health Concern Councillor who had lost his seat a few weeks earlier.
but lost Ryedale: Derwent to a Liberal (not Democrat) who had not contested the seat before
- a 2 member ward that had returned 2 Conservatives since at least 2003 apart from 2007 when a sole Conservative and a Liberal Democrat were elected.
A Liberal Democrat gained Huntingdonshire: Huntingdon East from UKIP who fell into third place behind the Conservatives.
- a 3 member ward that elects annually: Conservatives won in 2007, 2011 and 2015, Liberal Democrats in 2008, 2010 and 2012 with UKIP winning in 2014.
