Series 15 (Channel 4: Series 16)
Special: All-Women Special
First broadcast: Friday 13th July 2018
Katherine Ryan guest hosts a very special all female edition celebrating 100 years of women's suffrage. Roisin Conaty and Jessica Hynes take on Sara Pascoe and Lolly Adefope in the classic words and numbers quiz. Morgana Robinson appears in character as Natalie Cassidy alongside Susie Dent in Dictionary Corner, while maths whizz Rachel Riley looks after the numbers.
2. Episode Two
First broadcast: Friday 20th July 2018
Jimmy Carr hosts a brand new episode with Sean Lock and Katherine Ryan who take on Jon Richardson and Joe Wilkinson in the classic words and number quiz. Dr John Cooper Clarke joins Susie Dent in Dictionary Corner, while maths whizz Rachel Riley looks after the numbers.
3. Episode Three
First broadcast: Friday 27th July 2018
Sean Lock and Miles Jupp take on guest captain Alan Carr and Roisin Conaty in the classic words and number quiz. Ivan Brackenbury joins Susie Dent in Dictionary Corner.
4. Episode Four
First broadcast: Friday 3rd August 2018
Sean Lock and Rob Beckett take on Jon Richardson and Claudia Winkleman. Plus special guests Mr Swallow and Joe Wilkinson join Countdown regulars Susie Dent and Rachel Riley.
5. Episode Five
First broadcast: Friday 10th August 2018
Jimmy Carr hosts as Sean Lock and Phil Wang take on guest captain Alan Carr and Harriet Kemsley. Plus David O'Doherty and Joe Wilkinson join Countdown regulars Susie Dent and Rachel Riley.
6. Episode Six
First broadcast: Friday 17th August 2018
Sean Lock and Richard Ayoade take on Jon Richardson and Jessica Knappett. Plus special guests Alex Horne and the Horne Section join Susie Dent in Dictionary Corner, while maths whizz Rachel Riley looks after the numbers and letters.
7. Episode Seven
First broadcast: Friday 24th August 2018
Jimmy Carr hosts a brand new show, as Sean Lock and Kevin Bridges take on guest captain Joe Wilkinson and Victoria Coren Mitchell. Plus special guest Adam Kay joins Susie Dent in Dictionary Corner, while maths whizz Rachel Riley looks after the numbers.
8. Episode Eight
First broadcast: Friday 31st August 2018
Jimmy Carr hosts the last in the current series, as Sean Lock and Roisin Conaty take on guest captain Alan Carr and Joe Lycett. Plus special guest Spencer Jones joins Susie Dent in Dictionary Corner, while maths whizz Rachel Riley looks after the numbers and letters.
Christmas Special
First broadcast: Sunday 23rd December 2018
Sean Lock and Kathy Burke team up against Jon Richardson and David Mitchell. James Acaster joins Countdown's resident lexicographer Susie Dent in Dictionary Corner, while maths whizz Rachel Riley and comedian Joe Wilkinson are in charge of the numbers.