Johnny Flynn is a South African-English musician, singer-songwriter, and film and television actor.

Johnny Flynn plays as Dylan Witter in Genius.
Johnny Flynn is the top #1 member of the cast and appears in 22 episodes.

Samantha Colley plays as Mileva Marić, Dora Maar in Genius.
Samantha Colley is the top #2 member of the cast and appears in 20 episodes.

Clémence Guichard (born 30 October 1982), known professionally as Clémence Poésy, is a French actress and fashion model. After starting on the stage as a child, Poésy studied drama and has been active in both film and television since 1999, including some English-language productions. She is known for the roles of Fleur Delacour in the Harry Potter film series, Chloë in In Bruges, Rana in 127 Hours, Natasha Rostova in War and Peace, and the lead role as Elise Wassermann in the 24-episode series The Tunnel.

Clémence Poésy plays as Isabelle Carriere in Genius.
Clémence Poésy is the top #3 member of the cast and appears in 11 episodes.

Geoffrey Roy Rush (born 6 July 1951) is an Australian actor and film producer. As of November 2009, he was one of 25 people to have won the "Triple Crown of Acting": an Academy Award, a Tony Award and an Emmy Award. Apart from being nominated for 4 Academy Awards for acting (winning 1) and 5 BAFTA Awards (winning 3), he has also won 2 Golden Globe and 3 Screen Actors Guild Awards. Description above from the Wikipedia article Geoffrey Rush, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Geoffrey Rush plays as Albert Einstein in Genius.
Geoffrey Rush is the top #4 member of the cast and appears in 10 episodes.

José Antonio Domínguez Bandera (born August 10, 1960), known professionally as Antonio Banderas, is a Spanish actor, producer, director, and singer. He began his acting career at age 19 with a series of films by director Pedro Almodóvar and then appeared in high-profile Hollywood films, especially in the 1990s, including Assassins, Evita, Interview with the Vampire, Philadelphia, Desperado, The Mask of Zorro, Spy Kids, the Shrek sequels and Puss in Boots.

Antonio Banderas plays as Pablo Picasso in Genius.
Antonio Banderas is the top #5 member of the cast and appears in 10 episodes.

Alex Rich plays as Pablo Picasso in Genius.
Alex Rich is the top #6 member of the cast and appears in 10 episodes.

Richard Topol is an actor.

Richard Topol plays as Fritz Haber in Genius.
Richard Topol is the top #7 member of the cast and appears in 10 episodes.

Ralph Brown was born on June 18, 1957. He is an actor and writer.

Ralph Brown plays as Max Planck in Genius.
Ralph Brown is the top #8 member of the cast and appears in 10 episodes.

Courtney Bernard Vance (born March 12, 1960) is an American actor. Vance started his career on the Broadway stage in the original productions of August Wilson's Fences in 1985, John Guare's Six Degrees of Separation in 1990 and Nora Ephron's Lucky Guy in 2013 for which he won a Tony Award for Best Featured Actor in a Play. He is known for his roles in films such as Hamburger Hill (1987), The Hunt for Red October (1990), The Preacher's Wife (1996), Cookie's Fortune (1999), Terminator Genisys (2015), and Isle of Dogs (2018). Vance is also known for work on television on shows such as Law & Order: Criminal Intent, where he portrayed Assistant District Attorney Ron Carver. He also guest-starred on Law & Order, Picket Fences, The Closer, Revenge, Scandal, and Masters of Sex. He won acclaim for his portrayal of Johnnie Cochran in the FX limited series The People v. O. J. Simpson: American Crime Story (2016) for which he received the Primetime Emmy Award for Outstanding Lead Actor in a Limited Series or Movie. He recently appeared in the HBO television film, The Immortal Life of Henrietta Lacks (2017), National Geographic's limited series Genius: Aretha (2020), and the HBO drama series Lovecraft Country (2020) the latter of which earned him a Primetime Emmy Award for Outstanding Guest Actor in a Drama Series. He has been married to actress Angela Bassett since 1997. Vance is on the Board of Directors for The Actors Center in New York City, and is an active supporter of Boys & Girls Clubs of America. In 2019, Vance was appointed as the President of the Screen Actors Guild Foundation. Description above from the Wikipedia article Courtney B. Vance, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Courtney B. Vance plays as Johnnie Cochran in Genius.
Courtney B. Vance is the top #9 member of the cast and appears in 10 episodes.

Michael McElhatton (born 12 September 1963) is an Irish actor and writer. He is best known for playing the role of Roose Bolton in the HBO series Game of Thrones. He joined the series as a guest star in the second season, and continued to play this role until the sixth season, promoted to a regular cast member from the fifth season onwards.

Michael McElhatton plays as Jean de Merteuil in Genius.
Michael McElhatton is the top #10 member of the cast and appears in 8 episodes.