Arcadia Tom Stoppard

Characters of 1809

• Thomasina Coverly: The 13-year-old (later 16-year-old) daughter of Lord and Lady Croom, Thomasina is a precocious genius. She comes to understand chaos theory and the second law of thermodynamics, before either is established in the mathematical and scientific communities. Stoppard "apparently based"[3][4] the character on Lord Byron's daughter Ada Lovelace (Augusta Ada King, Countess of Lovelace). She was an English mathematician who conceptualised how Charles Babbage's Analytical engine could be used, foreseeing the binary computer.[5]
• Septimus Hodge: Thomasina's tutor, and the academic colleague and friend of Lord Byron (an unseen but important character). While teaching Thomasina, he works on his own research and has affairs with the older women of the house. When Thomasina is older, he falls in love with her; after her death, he becomes the "hermit of Sidley Park", working on her theories until his own death.
• Jellaby: The Crooms' butler. His chief functions are to spread gossip and to deliver letters.
• Ezra Chater: An unsuccessful poetaster staying at Sidley Park. His wife's romantic affairs lead him to challenge Septimus to a duel. Later, it is revealed that he is the amateur botanist "Mr. Chater," who dies of a monkey bite in Martinique, where he has travelled with his wife and Captain Brice.
• Charity Chater: Ezra Chater's wife. Though she, like Byron, never appears onstage, she plays a vital role. She sleeps with Septimus, and her repeatedly cuckolded husband challenges him to a duel. She sleeps with Lord Byron and gets him, Captain Brice, her husband and herself expelled from Sidley Park.
• Richard Noakes: Lady Croom's gardener. Throughout the play, he is working to transform Sidley Park's classical, Arcadia-like landscape into the popular Gothic style – which Lady Croom begrudgingly accepts. He is key in exposing Septimus's and Mrs. Chater's affair.
• Lady Croom: Thomasina's mother. She rules the Coverly estate with an iron fist, but flirts with Septimus and other gentlemen throughout the play. A second Lady Croom, the mother of Valentine, Chloe, and Gus in the modern half of the play, never appears on stage.
• Captain Brice: The brother of Lady Croom (of 1809). He is a sea captain who falls in love with Mrs. Chater. He takes her and her husband to the West Indies at the end of the play. After Mr. Chater's death, Captain Brice marries the widowed Charity Chater.
• Augustus Coverly: Thomasina's trouble-making younger brother. He appears in only a few brief scenes. (Gus and Augustus are played by the same actor.)

Characters of the present

• Hannah Jarvis: The author of a best-seller on Byron's mistress Lady Caroline Lamb. Hannah is researching the elusive hermit of Sidley Park, said to have lived there in the early 19th century. Hannah collaborates (warily) with Bernard and also with Valentine, though she rejects the romantic advances of both.
• Chloe Coverly: The 18-year-old daughter of the modern Lady Croom. While her mind is not as rigorous as Thomasina's, Chloe likes to propose wild ideas. She argues that the Newtonian universe has been destabilized by sex and the problems it causes. She tries to set up Hannah with Bernard, but ends up sleeping with him herself.
• Bernard Nightingale: A don at a modern university in Sussex, England. Bernard comes to Sidley Park hoping to work with Hannah on his theory about Lord Byron staying at the estate. Instead of seeking further evidence, he announces on TV his theory that Lord Byron killed Ezra Chater in a duel. At the end of the play, Hannah proves him wrong, much to his chagrin.
• Valentine Coverly: Chloe's older brother. A graduate student of mathematics, he pores over several old documents and comes to acknowledge Thomasina's genius.
• Gus Coverly: Valentine and Chloe's younger brother, who has been mute since the age of five. Gus helps to pass several important props from past to present, and helps connect key moments in the play. (Gus and Augustus are played by the same actor.)