A bombastic bloke who was often pictured in a pub with a pint in his hand, Farage was one of the founders of UKip, a party whose main goal is to leave the EU.
Cameron once described UKip as a bunch of "fruitcakes, loonies and closet racists".
But UKip's anti-establishment messages resonated with large numbers of voters, and pressure from UKip and the Eurosceptics in the Conservative Party led Cameron to promise a referendum on Britain's EU membership.
Farage's leadership - he took the helm in 2006 - helped transform UKip into something of a populist phenomenon.
In the 2014 European parliamentary elections, UKip became the first party in modern history other than the Conservative or Labour parties to win a British national election.
Charismatic and controversial, Farage is not like other politicians in Brussels.
Formerly a trader in London's financial district, he first won a seat in the European Parliament in 1999, where he quickly stood out.
"You have the charisma of a damp rag and the appearance of a low-grade bank clerk," he once told Herman Van Rompuy, the then-President of the EU.
But Farage was unable to translate his popularity as the leader of UKip into success at Westminster. He ran for a seat in the British general election last year and failed to win. He resigned as leader of UKip shortly afterward and then "unresigned" a few days later.
Farage insists this time it's for real. But he will not be fading from political life entirely - he will continue serving a two-year term as a member of the European Parliament in Brussels and Strasbourg, France.
This may not be welcome news for his colleagues in the European Parliament, whom he was accused of trolling last week when he turned to them and said "virtually none of you have ever done a proper job in your lives". In last year's general election, UKip was the third largest party, in terms of vote share.
But because of Britain's first-past-the-post voting system, the party only has one member of Parliament, Douglas Carswell, who incidentally is not a huge Farage fan.
But whether you like or loathe Farage, the beer-swilling politician has made an indelible mark on British politics.