Series 4

Jimmy Carr returns with Sean Lock and Jon Richardson, who are joined by Jonathan Ross and Roisin Conaty. David O'Doherty joins Susie Dent in Dictionary Corner, and Joe Wilkinson 'helps' Rachel Riley.

Guests are Freddie Flintoff and Rhod Gilbert. Henning Wehn joins Susie Dent in Dictionary Corner, while Joe Wilkinson 'helps' Rachel Riley provide the letters and numbers.

Jimmy Carr and team captains Sean Lock and Jon Richardson are joined by Josie Long and Rob Beckett. Vic Reeves joins Susie Dent in Dictionary Corner, while Joe Wilkinson 'helps' Rachel Riley.

Jimmy Carr hosts the comedy panel show's version of the famous quiz, with team captains Sean Lock and Jon Richardson joined by guests Jason Manford and Stephen Mangan. Countdown regular Susie Dent is in Dictionary Corner with Tim Key, while maths expert Rachel Riley provides the letters and numbers with a little `help' from Joe Wilkinson

Jimmy Carr hosts, alongside team captains Sean Lock and Jon Richardson, who are joined by Jo Brand and Claudia Winkleman. Bill Bailey joins Susie Dent in Dictionary Corner, while Joe Wilkinson 'helps' Rachel Riley provide the letters and numbers.

Jimmy Carr hosts, alongside team captains Sean Lock and Jon Richardson, who are joined by Bill Bailey and Josh Widdicombe. Jake Yapp joins Susie Dent in Dictionary Corner, while Joe Wilkinson 'helps' Rachel Riley provide the letters and numbers.

Jimmy Carr hosts the Cats/Countdown mash-up, with Sean Lock, Jon Richardson, Bob Mortimer and Richard Osman. Matthew Crosby joins Susie Dent in Dictionary Corner, and Joe Wilkinson 'helps' Rachel.