Warning! This article contains SPOILERS for Peaky Blinders season 6.The Shelby family is the most important group in cast of Peaky Blinders is what several of the show's most brutal betrayals and startling revelations are built upon.

With each season of Peaky Blinders, new characters were added to the Shelby family. Whether through marriage, birth, or discovering long-estranged children, the legendary Birmingham-based family just kept getting bigger and more complicated. The Shelbys also had a series of cousins and uncles on their Romani side who were either very distantly related or simply very good family friends, which makes it even harder to tell who's actually related to whom. As complicated as it is, most of the characters in Peaky Blinders have a fairly simple blood connection to one another, and the ones who don't can easily be explained.

Polly Gray

Spouse: Unnamed Husband

• Children: Michael Gray, Anna Gray

Polly Gray (Helen McCrory) was the sister of Arthur Shelby Sr. and the aunt of most of the cast of Peaky Blinders. Though she was their aunt, Polly effectively raised the main Shelby siblings. Prior to the start of the show, Polly was married to an unknown Romani man, and she kept his surname after his death. She had two children with her late husband, Michael and Anna Gray, who were both taken away from her care by the English government. Anna died in Australia, but Polly was able to reunite with Michael. In Peaky Blinders season 6, Polly was murdered by the Irish Republican Army.

Arthur Shelby Sr.

Spouse: Unnamed Wife

• Children: Arthur Shelby Jr., Thomas Shelby, John Shelby, Ada Thorne, Finn Shelby

Arthur Shelby Sr. (Tommy Flanagan) was the patriarch of the Shelby family and the father of the main group of Shelby siblings. The elder Arthur Shelby was an absent father who left his children in Polly's care. In Peaky Blinders season 1, he reunited with Arthur Shelby Jr. in a futile attempt to scam him out of money. Aside from parenting the main cast of the show, Arthur Shelby Sr. had very little impact on Peaky Blinders, and he died offscreen in 1924. The siblings did not grieve his death.

Arthur Shelby Jr.

Spouse: Linda Shelby

• Children: Billy Shelby

Arthur Shelby Jr. (Paul Anderson) was the firstborn son and oldest of the main Shelby siblings. Despite being the oldest, Arthur was not the leader of the Peaky Blinders or the legitimate Shelby Company Limited, and he instead acted as Tommy's muscle. Arthur married Linda (Kate Phillips) before Peaky Blinders season 3, and they had one son, Billy, together. Linda and Arthur were eventually separated after her religious views conflicted too much with Arthur and the Peaky Blinders' illegal activity. As of Peaky Blinders season 6, Arthur was still alive and working with Tommy.

Thomas Shelby

Spouses: Grace Burgess, Lizzie Stark

• Children: Erasmus "Duke" Shelby, Charles Shelby, Ruby Shelby

Thomas Shelby (Cillian Murphy), better known as Tommy, was the second oldest brother of the Shelby siblings, but he rose to lead the Peaky Blinders. Grace Burgess (Annabelle Wallis), who spied on the Peaky Blinders and seduced Tommy, revealed that she was pregnant with his first legitimate son, Charles. Tommy then married Grace in Peaky Blinders season 3, though Grace would soon be killed during one of Luca Changretta's (Adrien Brody) attempts on Tommy's life. Tommy would later marry former prostitute Lizzie Stark (Natasha O'Keeffe) and have a daughter, Ruby, with her.

Peaky Blinders season 6 further complicated Tommy's place in the Shelby family tree. After Ruby fell ill, Tommy discovered that a Romani woman had put a curse on her, and she died of consumption. After Ruby's funeral, Tommy also learned that he had an illegitimate son with Zelda, a woman he knew before he was drafted to fight in World War I. Tommy accepted his firstborn son, Erasmus "Duke" Shelby (Conrad Khan), into the Shelby family, and he became a major member of the gang.

John Shelby

Spouses: Martha Shelby, Esmé Lee

• Children: Katie Shelby, six other unnamed children

Though John Shelby (Joe Cole) was the second-youngest brother of the Shelby siblings, he had the most children. Prior to Peaky Blinders season 1, John was married to a woman named Martha, and they had four children together. After Martha's death, John couldn't care for his children alone, so Tommy arranged a marriage between him and a Romani woman named Esmé Lee (Aimee-Ffion Edwards). John and Esmé had another three children together, all of whom remained unnamed. John was shot and killed by Luca Changretta's men in Peaky Blinders season 4, and Esmé took their children to live with a Romani group.

Ada Thorne

Spouse: Freddy Thorne

• Children: Karl Thorne, Elizabeth Younger

Ada Thorne (Sophie Rundle) was the only daughter and second youngest of the main Shelby siblings. In Peaky Blinders season 1, Ada married Tommy's wartime friend and Communist organizer Freddy Thorne, and she kept his surname after his death. Ada and Freddy had one child, who they named Karl. Later, in Peaky Blinders season 4, Ada began a relationship with Ben Younger (Kingsley Ben-Adir). Though they didn't officially marry, Ada gave birth to his daughter, Elizabeth Younger, just after Ben was assassinated for investigating Oswald Mosley (Sam Claflin). As of Peaky Blinders season 6, Ada has not remarried.

Michael Gray

Spouse: Gina Nelson

• Children: Laurence Gray

Michael Gray (Finn Cole) was Polly Gray's only living child and the only living member of her branch of the Shelby family tree. As a child, Michael was taken from Polly's custody because the police found an illegal spirit still in her home. He was then raised in the English countryside, and his adoptive family renamed him Henry Johnson. When Polly tracked Michael down in Peaky Blinders season 2, he decided to move to Birmingham and the Peaky Blinders.

Eventually, in Peaky Blinders season 4, Tommy effectively exiled Michael to the United States. Though it was a punishment, Tommy allowed Michael to stay in the Shelby family business and expand the company's influence to America. Michael later married an American woman named Gina Nelson (Anya Taylor-Joy), and they had a son named Laurence together. In Peaky Blinders season 6, Tommy killed Michael after a lengthy battle between the cousins.

Finn Shelby

Spouse: Mary Bone

• Children: None

Finn Shelby (Harry Kirton) was the youngest of the Shelby siblings and the last child of Arthur Shelby Sr. In the early seasons of Peaky Blinders, Finn was too young to contribute much to the gang's operation beyond acting as a lookout. As he aged, he took a more involved role in the gang, though he was also looked down upon. In Peaky Blinders season 6, Finn married Mary Bone (Abbie Hern). Duke Shelby eventually banished Finn from the family after he refused to kill Billy (Emmett J. Scanlan), the informant who told the IRA about the plan to assassinate Oswald Mosley.

Erasmus "Duke" Shelby

Spouse: Unmarried

• Children: None

Duke Shelby, born Erasmus, was technically the firstborn son of Tommy, though his father was unaware he existed until Peaky Blinders season 6. Duke lived with his mother, Zelda, in a Romani group for 19 years, and as such didn't know any of the other Shelby family . Despite being just seven years younger, Duke is technically Finn's nephew. He also displayed quite a few similarities to Tommy despite not knowing his father for the majority of his life, such as their shared ability to predict others' actions and willingness to listen to people like Charlie Strong.