Stephen Fry considers some incomprehensible questions with Sue Perkins, Ross Noble, Professor Brian Cox and Alan Davies.

Stephen asks unanswerable questions with an international flavour. With Jack Dee, David Mitchell, Bill Bailey and Alan Davies.

Stephen Fry asks some intelligent questions. With Jo Brand, David Mitchell, Phill Jupitus and Alan Davies.

In a special Christmas edition, Stephen Fry looks at ice. With contestants Ross Noble, Sean Lock, Brian Blessed and Alan Davies.

Stephen Fry investigates an imbroglio of issues with John Bishop, Frank Skinner, Sean Lock and Alan Davies.

Stephen Fry plays I-Spy with Sandi Toksvig, Lee Mack, Jimmy Carr and Alan Davies.

Stephen Fry looks at insects and other invertebrates. With Sarah Millican, Jimmy Carr, Johnny Vegas and Alan Davies.

Stephen Fry talks about indecision with Jimmy Carr, Rich Hall, Phill Jupitus and Alan Davies.

Stephen Fry addresses inequality and injustice with Sandi Toksvig, Clive Anderson, Henning Wehn and Alan Davies.

Stephen Fry investigates Illness with Jo Brand, Ben Goldacre, Andy Hamilton and Alan Davies.

Stephen Fry casts light on the subject of Infantile. With Lee Mack, Ronnie Ancona, Dave Gorman and Alan Davies.

Stephen Fry casts light on the subject of illumination. With Jack Dee, Chris Addison, Rich Hall and Alan Davies.

Stephen Fry investigates the Immortal Bard with Sue Perkins, Bill Bailey, David Mitchell and Alan Davies in a special show for the Cultural Olympiad.

Stephen Fry takes a lazy look at idleness with Ross Noble, Dara Ó Briain, Jeremy Clarkson and Alan Davies.

Stephen Fry waxes inventive with Nina Conti, Sean Lock, Bill Bailey and Alan Davies.

Stephen Fry asks some taxing questions about things that start with I, with Sandi Toksvig, Al Murray, Dara Ó Briain and Alan Davies.

Collection of highlights from QI Series 9 - aka the letter 'I' series.

Second collection of highlights from QI Series 9 - aka the letter 'I' series.