Child psychiatrist Martin Dysart is the first character introduced in Equus and the last to speak at the play's end. His commentary often serves as a form of narration for the play. Dysart is a middle-aged man who has enjoyed some success in his career but worries he is robbing his patients of the things that make them unique. His lifeless marriage and respectable profession clash with his secret dream of running away to the Mediterranean coast.
Seventeen-year-old stable hand Alan Strang is Dysart's latest patient, brought to the clinic after a seemingly inexplicable act of violence against the horses in his care. Over the course of the play, he describes incidents from his childhood that led to his semireligious fascination with horses.
Frank Strang is a middle-aged printer with honest, working-class values. He fails to fully understand what drove his son to attack the horses but blames his wife for filling Alan's head with religious stories and ideas. The conflict between Frank's atheism and Dora's religiosity is a defining feature of the Strang household.
Dora Strang, Alan's mother, is a highly religious middle-aged woman whose current working-class lifestyle does not suit her highbrow pretensions. She clashes with her husband about everything from Christianity to television. Initially guilt-ridden and confused about her son's assault on the horses, she eventually chalks his behavior up to demonic possession.
Hesther Salomon is a local magistrate whose caseload involves some disturbing juvenile crimes. After much arguing with her fellow judges, she sends Alan to Dysart in order to divert the boy from a likely prison sentence. She has more faith in the enterprise of child psychiatry than Dysart seems to.
Jill Mason, the stable hand who works for Mr. Dalton, is a seemingly normal young woman in her early 20s. Obviously fond of Alan, she gets him a job at Dalton's and, near the end of the play, asks him on a date.