Olly Alexander (born Oliver Alexander Thornton, 15 July 1990), is an English singer, songwriter and actor. His music is released under the name Years & Years.

Olly Alexander plays as Self in It's a Sin.
Olly Alexander is the top #1 member of the cast and appears in 17 episodes.

Keeley Hawes is an English actress, born in London and educated at the Sylvia Young Theatre School. She began her career in a number of literary adaptations, including Our Mutual Friend (1998), Wives and Daughters (1999), Tipping the Velvet (2002), and The Canterbury Tales (2003). She portrayed Zoe Reynolds in the BBC espionage drama series Spooks from 2002 to 2004, followed by her co-lead performance as Alex Drake in Ashes to Ashes (2008–2010), for which she won a Glamour Award. She played leading roles in the 2010 revival of Upstairs, Downstairs, the limited series The Casual Vacancy (2015), The Missing (2016), and the ITV comedy-drama The Durrells (2016–2019). Hawes was nominated for the BAFTA TV Award for Best Actress for her performance in Jed Mercurio's police procedural Line of Duty as DI Lindsey Denton. She teamed again with Mercurio for the 2018 thriller Bodyguard in which she played Home Secretary Julia Montague. Hawes has also appeared in films, including Death at a Funeral (2007) and High-Rise (2015), and she provided the voice of Lara Croft in a series of Tomb Raider video games.

Keeley Hawes plays as Priscilla Garrick in It's a Sin.
Keeley Hawes is the top #2 member of the cast and appears in 6 episodes.

Lydia West is a British film and television actress.

Lydia West plays as Reilly Clayton in It's a Sin.
Lydia West is the top #3 member of the cast and appears in 6 episodes.

Callum Scott Howells (born 1999) is an actor, known for It's a Sin (2021).

Callum Scott Howells plays as Colin Morris-Jones in It's a Sin.
Callum Scott Howells is the top #4 member of the cast and appears in 3 episodes.

Omari Douglas plays as Roscoe Babatunde in It's a Sin.
Omari Douglas is the top #5 member of the cast and appears in 3 episodes.

Nathaniel Curtis plays as Ash Mukherjee in It's a Sin.
Nathaniel Curtis is the top #6 member of the cast and appears in 3 episodes.

Neil Ashton plays as Grizzle in It's a Sin.
Neil Ashton is the top #7 member of the cast and appears in 3 episodes.