First elected in 2012 to replace Police Authorities made up of councillors there are 42 Police & Crime Commissioners (PCCs) in England & Wales.
In London and Greater Manchester the elected mayor is the Police Authority.
Currently there are 20 Conservative, 16 Labour, 2 Plaid Cymru and 4 Independent commissioners although all sign an Oath of Impartiality on taking up the position.
In some areas, including Staffordshire, the PCC has also replaced the Fire Authority.
PCCs are tasked with securing the maintenance of an efficient and effective police force within their area, and to hold the Chief constable to account for the delivery of the police and crime plan. PCCs are charged with holding the police fund (from which all policing of the area is financed) and raising the local policing precept from council tax. PCCs are also responsible for the appointment, suspension and dismissal of the Chief Constable. In Staffordshire the PCC has similar responsibilities for the Fire & Rescue Service plan, budget and Chief Fire Officer.
Read more on Wikipedia here, including a list of current PCCs.
The Association of Police and Crime Commissioners has further information here.