Brain of Britain is a BBC radio general knowledge quiz, broadcast on BBC Radio 4.

It began as a slot in What Do You Know? in 1953 before becoming a programme in its own right in 1967. It was chaired by Franklin Engelmann until his death in 1972.

The format of the quiz is simple. A contestant is asked a question; if he answers it correctly he gets a point and is asked another. If he gets one wrong the question is offered to the other contestants via silent buzzer, and the questions move to the next contestant. If a contestant gets five questions correct in a row then he gets a bonus point and the questions move to the next contestant. The contestant with the most points at the end of the programme wins.

The show also features "Beat The Brains", in which a pair of questions submitted by a listener is read, winning a book token if the contestants fail to answer one.

Brain of Britain has been hosted by Robert Robinson for most of its life, although during his illness the 2004 series was hosted by Russell Davies. The question setter, to whom the host defers if an answer is on the cusp of being right, is present at recordings but silent. He is traditionally known by a pseudonym. For many years Ian Gillies fulfilled the role, taking the name Mycroft (from Mycroft Holmes, older and wiser brother of Sherlock). After his death in April 2002, the new question setter was Kevin Ashman, who has the distinction of winning both Brain of Britain and Mastermind. He chose to be known as Jorkins, a character in Dickens' David Copperfield.

For much of its life the theme music of Brain of Britain was the opening of the fourth movement of Mozart's Eine Kleine Nachtmusik, but in a 'modernised' version by Waldo de Los Rios. This choice was the subject of frequent complaints from classical music fans (with whom the show was popular) and presenter Robert Robinson described it on air as "Mozart plus sacrilege". The theme was changed to a more conventional version in the early nineties.

Every three years, the three most recent champions compete for the Brain of Brains title, most recently held in 2004. The three winners of Brain of Brains themselves compete for the title Top Brain, held every nine years, with Kevin Ashman the most recent winner in 1998.