William Nigel Paul Cash, usually Bill Cash (born 1940) is an English Tory politician, Member of Parliament and opposition front-bencher.

He was educated Stonyhurst College and Lincoln College, Oxford. He is a professional solicitor and runs a law firm William Cash & Co. Apart from this he is a member of the wealthy Cash (nametag manufacturers) family. His daughter Laetitia is prominent in society circles.

He entered Parliament in 1984, when he became MP for Stafford in a by-election; since 1997 he has been MP for Stone, Staffordshire. He has served on various committees. He is known as a strong eurosceptic and at one point was ringleader of a rebellion over the Maastricht treaty that almost brought down John Major's government. He was described by Ken Clarke as the most euro-sceptic Member of Parliament. He is president of the euro-sceptic European Foundation which was created during the Maastricht Rebellion, the funding for which he organised.

After he became leader, fellow rebel Iain Duncan Smith gave him the post of shadow Attorney General in 2001, and in 2003 was made a spokesman on Constitutional Affairs.