Perry Edward Smith - One of the two murderers of the Clutter family. He is a short with a large torso but small legs. His childhood was lonely and disorganized. His criminal record seems to be a natural extension of the strange environments in which he grew up.
Richard Eugene Hickock – The other of the two murderers of the Clutter family. Also a small man, Dick grew up in Kansas, was married twice, and is jailed for passing bad checks.
- These two characters above are key. They are create the entire story and they make the book even more interesting. Dick and Perry are the murders that killed the family and they keep the reader wondering.
Herbert Clutter - The father of the Clutter family. He has four children. His large property, River Valley Farm, keeps him moderately wealthy with his large, successful farm.
Bonnie Clutter - Herbert's wife, Bonnie, cannot keep up with his public image as a leader, and she withdraws into the home.
Nancy Clutter - Along with Kenyon, one of the two youngest Clutter children. They both still live at home. She is "the darling" of the town, a class president and future prom queen. Like her father, she is very organized.
Kenyon Clutter - An awkward 15-year-old, Kenyon loves to tinker with carpentry and machines.
- The entire Clutter family are the characters in the story that the reader feels sympathy for. The children especially you feel for them because they were so gruesomly murdered. Because they live the perfect farm life with a cute family its easy to feel sympathy. The Clutters are also the key part in the plot without their murders their would be no problem.
Bobby Rupp - Nancy's steady boyfriend, Bobby lives nearby.
Alvin Dewey - An investigator for the Kansas Bureau of Investigation (KBI), Dewey is the agent responsible for much of western Kansas. He becomes very involved in the case.
Harold Nye - One of Dewey's principal KBI assistants. Nicknamed "Brother Nye," he is the youngest of the group. During the capture and interrogation of Smith and Hickock, he has the flu.
Roy Church - The oldest of the KBI assistants, Church is nicknamed "Curly" and is supposedly the fastest draw in Kansas.
Clarence Duntz - Another of the three KBI assistants, Duntz is a burly man with a broad face.
Tex John Smith - Perry's father, Tex is a kindly backwoodsman who taught Perry to bake bread, but who never comes to see his son in jail.
Susan Kidwell - Nancy's best friend, Susan lives in Holcomb.
Willie-Jay - Assistant to the chaplain of Lansing, the Kansas state prison, Willie-Jay becomes a kind of mentor to Perry.
Floyd Wells - An inmate at Lansing prison. After Perry leaves on parole, he became Dick's cellmate. He is a former employee of Herbert Clutter, and he tells Dick about the ranch and the layout of the house.
Lowell Lee Andrews - Andrews was a young college student who murdered his family. He is a schizophrenic. Several of his years on death row overlap with those of Dick and Perry. Perry resents the fact that Andrews is highly educated.
Mr. Helms - An employee of River Valley Farm.
Alfred Stoecklein - An employee of River Valley Farm. He and his wife live on the property.
Bess Hartman - The proprietor of Hartman's Cafe. She has a thick skin and scolds her customers when they gossip too much about the Clutter murders.
Barbara Johnson - Perry's only living sister. She lives in San Francisco and is married.
Don Cullivan - An old army friend of Perry's who starts a correspondence with him upon reading about the case in the newspaper.
