The narrators—a group of middle-age men recounting their experiences as 16- and 17-year-old boys.
Mr. Lisbon—the father of the five Lisbon girls and a math teacher at the private preparatory school the narrators and the Lisbons attend.
Mrs. Lisbon—the mother of the five Lisbon sisters.
Cecilia Lisbon—the youngest Lisbon sister and the first to commit suicide; she jumps out of a third-story window.
Lux Lisbon—the second youngest sister and the most attractive, outgoing of the Lisbon girls; she kills herself by carbon monoxide poisoning.
Bonnie Lisbon—the middle sister, quiet and religious; she hangs herself.
Mary Lisbon—the second oldest sister, severe and proper; she is the last to die, via sleeping pills.
Therese Lisbon—the oldest sister, awkward and intellectual; she overdoses on sleeping pills.
Trip Fontaine—the school heartthrob who is a peer of the narrators and briefly has a relationship Lux.
Neighbors—a collection of minor characters who live on the same street as the Lisbons and who provide the narrators with memories and opinions of the Lisbons.
Dr. Hornicker—a hospital psychiatrist who examines Cecilia, Lux, and Mary.
Paramedics—two men who tend to the Lisbon sisters after each suicide incident.
Mrs. Karafilis—the immigrant grandmother of one of the neighborhood boys.
Father Moody—a Catholic priest who attempts to console the Lisbons.