Billy Pilgrim: Billy is the protagonist of the novel. He is unstuck in time and travels to different moments in his life. He grew up a fearful child and was taken prisoner by the Germans during WWII. Billy was working as prison labor in Dresden when an allied bombing raid destroyed the city and most of its inhabitants. After the war Billy finished school, had a nervous breakdown, married the daughter of the dean of the school, became a successful optometrist and later survived a plane crash that took the life of all the other passengers. On the night of his daughter's wedding he was kidnapped by aliens from the planet Tralfamadore and put on display in a zoo where he mated with movie star Montana Wildhack. He has foreseen that his own death will come at the hands of Paul Lazzaro following a speech in Chicago.
Valencia Pilgrim: Billy's overweight, unattractive wife who loves him dearly. Valencia's father sets Billy up in business and as a result Billy becomes very wealthy. Valencia dies of carbon monoxide poisoning when she rushes to the hospital in Vermont where Billy is recovering after the plane accident.
Barbara Pilgrim: Billy and Valencia's daughter who marries young and then assumes responsibility for her father after her mother dies and Billy begins talking openly about his experience with the Tralfamadorians.
Robert Pilgrim: Billy and Valencia's son who is a teenage delinquent but joins the Marines and returns from Vietnam a highly decorated Green Beret.
Bernard V. O'Hare: Vonnegut's war buddy who also survived the destruction of Dresden. O'Hare is a district attorney in Pennsylvania when Vonnegut contacts him to see what he remembers of the war. Vonnegut and O'Hare have a pleasant trip when they return to Dresden after the war.
Kurt Vonnegut: The author of the book and also one of its characters. Not only are the first and last chapters from Vonnegut's perspective but twice during the plot he interjects that he was present at that moment of the story.
Kilgore Trout: A largely unknown science-fiction writer who becomes Billy's favorite author. Billy eventually meets Trout, who supports himself by managing a group of child newspaper carriers, and invites the near-do-well author to his anniversary party. Trout appears in several other Vonnegut novels and represents what Vonnegut might have come to if his writing career been unsuccessful.
Roland Weary: Roland and Billy are trapped behind enemy lines during the Battle of the Bulge and are taken prisoner together. Roland has trouble keeping friendships and lashes out violently when he feels rejected. Thanks to his father, he has an obsession with instruments of torture. He insists on pushing Billy to continue the struggle to return to friendly lines and after they are taken prisoner blames Billy for his capture. Before Roland dies in the boxcar on the way to the prison he makes Paul Lazzaro promise to kill Billy for him.
Paul Lazzaro: Holds the dying Weary in his arms and promises to revenge his death by killing Billy Pilgrim. Lazzaro is a vengeful ex-car thief whom Vonnegut characterizes as akin to a rabid dog. While recovering from a broken arm after trying to steal cigarettes, Lazzaro tells Billy that he will kill him at some point and that Billy should relax and enjoy the time he has left.
Edgar Derby: A high school teacher who is one of the POWs in Billy's group. Derby is the oldest of the POWs and he assumes responsibility for their well being. According to Vonnegut he is the only true character in the novel and his best moment is when he rebukes the recruiting efforts of Nazi sympathizer Howard W. Campbell, Jr. Derby's death at the hands of a German firing squad for stealing a teapot, while never fully described serves as the novel's climax.
Eliot Rosewater: Shares a room with Billy in the psychiatric hospital where he introduces Billy to the works of Kilgore Trout. Rosewater is the protagonist of another Vonnegut novel God Bless You, Mr. Rosewater.
Howard W. Campbell, Jr. : An American playwright who serves the Nazis by composing and publishing anti-American propaganda. Edgar Derby rebukes him when he tries to convince the POW's to join the Nazi army. Campbell is the protagonist of another Vonnegut novel Mother Night.
Montana Wildhack: a pornographic movie starlet kidnapped at age twenty by the Tralfamadorians to be Billy's mate. She and Billy learn to trust each other and they have a child while on display in the zoo. While in New York Billy sees a blue movie staring Montana and reads a magazine article that suggests she was killed by the mob but he knows she is on Tralfamadore.
Bertram Copeland Rumfoord: an extremely virile and outgoing septuagenarian who shares a hospital room with Billy after the plane crash. Rumfoord, who is recovering from a skiing accident, is working on a history of the U.S. airforce and though he initially detests and mistrusts Billy he comes to believe that Billy was in Dresden at the time of its destruction.
Lily Rumfoord: Bertram's very young, very beautiful very dim wife.
Werner Gluck: a teenage guard in Dresden who is Billy's distant cousin though neither of them know it.