Damian Watcyn Lewis (born 11 February 1971) is an English actor and producer. He is probably best known in the United States for starring as Detective Charlie Crews in the NBC drama Life as well as portraying Major Richard Winters in the HBO miniseries Band of Brothers. Description above from the Wikipedia article Damian Lewis, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Damian Lewis plays as Bobby "Axe" Axelrod in Billions.
Damian Lewis is the top #1 member of the cast and appears in 55 episodes.

Maggie Siff (born June 21, 1974) is an American actress best known for her television roles, notably department-store heiress Rachel Menken Katz on the AMC drama Mad Men and Dr. Tara Knowles on the FX drama Sons of Anarchy. She also played a role in the 2009 film Push, as Teresa Stowe and in the 2010 film Leaves of Grass as Rabbi Renannah Zimmerman. Description above from the Wikipedia article Maggie Siff, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Maggie Siff plays as Wendy Rhoades in Billions.
Maggie Siff is the top #2 member of the cast and appears in 55 episodes.

Malin Maria Akerman (born 12 May 1978) is a Swedish-American raised in Canada, actress, producer and model. In the early 2000s, she had several small television and film parts in both Canadian and American productions, including The Utopian Society (2003) and Harold & Kumar Go to White Castle (2004). Following a supporting role on the HBO mockumentary sitcom The Comeback (2005), she gained her first co-starring roles in the romantic comedy films The Heartbreak Kid (2007) uncredited in The Invasion (2007) 27 Dresses (2008). She played the female lead in Watchmen (2009) as Silk Spectre II, a role for which she was nominated for a Saturn Award for Best Supporting Actress. In 2009, Åkerman had supporting and starring roles in the romantic comedies The Proposal and Couples Retreat. From 2010 to 2016, she starred on the Adult Swim comedy series Childrens Hospital. In 2012, she co-starred in the comedy Wanderlust and the musical film Rock of Ages. She had her first lead television role with the short-lived ABC comedy series Trophy Wife (2013–2014). She later co-starred in the film I'll See You in My Dreams (2015) and the action film Rampage (2018). Since 2016, Åkerman has had a main role on the Showtime drama series Billions as Lara Axelrod. Apart from acting and modelling, Åkerman had a brief music career as the lead vocalist for alternative rock band The Petalstones in the early 2000s, but eventually left to focus on her acting career. She has been married twice, first from 2007 to 2014 to Petalstones drummer Roberto Zincone, with whom she has a son, and, since 2018, to English actor Jack Donnelly.

Malin Åkerman plays as Black Widow, Nerd's Niece in Billions.
Malin Åkerman is the top #3 member of the cast and appears in 40 episodes.

Jeffrey DeMunn (born April 25, 1947) is an American theatre, film and television actor.He is known as a favorite of director Frank Darabont, who has cast him in all four of his films, The Green Mile, The Shawshank Redemption, The Majestic and The Mist (he also appeared in the 1988 remake of The Blob, which Darabont co-wrote). He also has an extensive television résumé, appearing in shows such as Kojak, Law & Order, and two of its spin-offs, SVU and Trial by Jury. He has been involved in more Stephen King adaptations than any other actor. He has acted in film adaptations of Rita Hayworth and Shawshank Redemption, The Green Mile, The Mist and the T.V. miniseries Storm of the Century. He also narrated the audiobooks for Dreamcatcher and The Colorado Kid. In 1995, he won a CableACE Award as Best Supporting Actor in a Movie or Miniseries for his portrayal of serial killer Andrei Chikatilo in the HBO film Citizen X. Description above from the Wikipedia article Jeffrey DeMunn, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Jeffrey DeMunn plays as Charles Rhoades, Sr. in Billions.
Jeffrey DeMunn is the top #4 member of the cast and appears in 24 episodes.

Asia Kate Dillon was born on November 15, 1984 in Ithaca, New York, USA. They are known for playing Brandy Epps in Orange Is the New Black and Taylor Mason in Billions. Their role on Billions is the first gender non-binary character on American television. Dillon identifies as non-binary and uses singular they pronouns.

Asia Kate Dillon plays as Taylor Mason in Billions.
Asia Kate Dillon is the top #5 member of the cast and appears in 24 episodes.

Condola Rashad was born on December 11, 1986 as Condola Phylea Rashad. She is an actress.

Condola Rashad plays as Meghan Markle (voice) in Billions.
Condola Rashad is the top #6 member of the cast and appears in 12 episodes.

Kelly AuCoin is an American stage, film and television actor from Oregon. He is a graduate from Oberlin College.

Kelly AuCoin plays as 'Dollar' Bill Stern in Billions.
Kelly AuCoin is the top #7 member of the cast and appears in 12 episodes.

Toby Leonard Moore is an actor, producer and writer.

Toby Leonard Moore plays as Gordon Piper in Billions.
Toby Leonard Moore is the top #8 member of the cast and appears in 10 episodes.

David Costabile (/ˈkɒstəbəl/; born January 9, 1967) is an American actor. He is best known for his television work, having appeared in supporting roles in several television series such as Billions, Breaking Bad, Damages, Flight of the Conchords, Suits, The Wire, and The Dirt. He has also acted on film and in Broadway theatre

David Costabile plays as Grant Savage in Billions.
David Costabile is the top #9 member of the cast and appears in 6 episodes.

Paul Edward Valentine Giamatti (born June 6, 1967) is an American actor. Giamatti began his career as a supporting actor in several commercially successful and critically acclaimed films produced during the 1990s including Private Parts, The Truman Show, Saving Private Ryan, The Negotiator, and Man on the Moon, before earning lead roles in several projects in the 2000s including American Splendor, Sideways, Cinderella Man, The Illusionist, John Adams, Cold Souls, and Barney's Version. Description above from the Wikipedia article Paul Giamatti, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Paul Giamatti plays as Christian Barbrow in Billions.
Paul Giamatti is the top #10 member of the cast and appears in 0 episodes.