Jimmy Carr hosts a combination of the comedy panel show and the long-running words and numbers quiz, with comedians putting their mental agility to the test. Regular Countdown mathematician Rachel Riley and lexicographer Susie Dent are on hand to adjudicate
| role | name |
|---|---|
| Self - Host | Jimmy Carr |
| Self - Lexicographer | Susie Dent |
| Self - Voice-Over | John Pohlhammer |
| Self - Voiceover | John Pohlhammer |
| Self - Arithmetician | Rachel Riley |
| Self - Mathematician | Rachel Riley |
| Self | Rachel Riley |
| Fabio | Robert Deaton |
| Self - Team Captain | Jon Richardson |
| Self - Contestant | Jon Richardson |
| Self - Team Captain | Sean Lock |
| Self - Contestant | Sean Lock |
| Self | Joe Wilkinson |
| Self - Contestant | Joe Wilkinson |
| Self - Special Guest | Joe Wilkinson |
| Self - Contestant | Roisin Conaty |
| Self - Team Captain | Roisin Conaty |
| Self - Guest Team Captain | Roisin Conaty |
| Self - Dictionary Corner Guest | David O'Doherty |
| Self - Contestant | David O'Doherty |
| Self - Special Guest | David O'Doherty |
