Watch QI XL Season 9 Full Episodes

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

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

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

Stephen Fry comes over all infantile with Ronni Ancona, Dave Gorman, Lee Mack and Alan Davies.

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

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

Stephen Fry hosts an extended version of the quiz with a difference, asking questions about inequality and injustice and awarding points for the most...

Stephen Fry hosts an extended version of the quiz with a difference, joined by comics Sue Perkins and Ross Noble, physicist Brian Cox and regular...

Stephen Fry waxes inventive with Nina Conti, Sean Lock, Bill Bailey 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 investigates an imbroglio of issues with John Bishop, Frank Skinner, Sean Lock and Alan Davies.

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

Stephen Fry hosts the mind-expanding quiz in which the aim is to be interesting. Stephen plays I-Spy with Sandi Toksvig, Lee Mack, Jimmy Carr and...

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