Aamons is the Finnish architect who designed Julian Castle's charity hospital and Frank Hoenikker’s house (once his own house) over the waterfall on San Lorenzo. He was Mona's biological father.
Bokonon (Lionel Boyd Johnson)
Lionel Boyd Johnson is a black Episcopalian from Tobago who has been around the world and is washed ashore on San Lorenzo with his white friend, Earl McCabe. They try to turn the impoverished island of San Lorenzo into a utopia. After that fails, he becomes Bokonon, a prophet offering the people of San Lorenzo hope through the lies of his religion, Bokononism. He and his religion are outlawed, but he records his teachings in the Books of Bokonon, and lives in hiding in the jungle.
Dr. Asa Breed
Dr. Asa Breed was Felix's supervisor at the Research Laboratory of the General Forge and Foundry Company where Felix helped develop the atomic bomb. Jonah interviews Dr. Breed, but Dr. Breed is offended by Jonah's questions because he thinks Jonah is a yellow journalist out to prove that scientists are indifferent to the plight of humanity. He tells Jonah about Felix's ideas of ice-nine, but he denies that Dr. Hoenikker had actually created it. Asa Breed was once engaged to Emily Hoenikker and many believe the Hoenikker children are his.
Marvin Breed is Asa Breed's brother, who owns and operates the tombstone shop in Ilium. He, like his brother Asa, was in love with Emily Hoenikker before she met Felix.
Julian Castle is a millionaire, the heir of the Castle Sugar Company who exploited the natives of San Lorenzo. He changes and becomes a philanthropist who builds and runs the House of Hope and Mercy in the Jungle for twenty years. A devout Bokononist, he administers the outlawed Bokononist last rites to his patients when they die. He teaches Jonah a great deal about the island and Bokononism.
Philip Castle is the handsome young son of Julian Castle, raised as a Bokononist with the young Mona, whom Philip has always loved. He is the owner and manager of Casa Mona, the hotel at which Jonah stays during his visit to San Lorenzo. He is still in love with Mona and makes a giant mosaic of her in the hotel lobby. He is the author of the only history of San Lorenzo.
Harrison Connors was Felix Hoenikker’s lab assistant and married Angela Hoenikker to get her share of ice-nine. He moved to Indianapolis and founded a weapons manufacturing company for the U.S. government.
H. Lowe and Hazel Crosby are the bicycle manufacturers from Chicago whom Jonah met on the plane to San Lorenzo. They tell him about the hook, a form of punishment on the island, and they gossip that Horlick Minton is a Communist. Hazel is happy that Jonah, Newt, and Angela are Hoosiers, like she is. The Crosbys are in the group of the last people on earth as they survive the intitial disaster of ice-nine and cheerfully set themselves up as a Swiss Family Robinson.
Miss Faust is Dr. Breed's secretary at the Laboratory. She shows Jonah Fexlix Hoenikker’s lab and tells stories about him.
The Girl Pool
The Girl Pool is the anonymous group of typists in the basement of the Laboratory of the General Forge and Foundry Company in Ilium, New York. They surface once a year for the Christmas party.
Angela is Felix Hoenikker's six-foot tall, unattractive oldest child. After her mother died in childbirth with Newt, Felix withdrew Angela from school to take care of him, Frank, and Newt. Despite her unhappiness, Angela believes her father is an unappreciated genius. After her father's death, Angela gives the secret of ice-nine to Harrison C. Conners, a scientist involved with top secret weapons research for the U.S. government, in return for his agreement to marry her. She dies playing her one consolation, the clarinet.
Emily is Felix Hoenikker's wife and the mother of Newt, Angela, and Frank. She died when giving birth to Newt. Felix did not show much attention to his wife when she was alive, and her death did not seem to touch him. The children use their father’s Nobel Prize money to build her a twenty-foot funeral marker.
Felix Hoenikker won the Nobel prize in physics and was one of the fathers of the atomic bomb. The inventor of ice-nine, he left the creation to his three children Newt, Angela, and Frank. Felix was always engrossed in his work and showed little concern for his wife or family or any other people. Science was child’s play to him, and he felt no responsibility for the effects of his inventions. He died peacefully in his cottage on Cape Cod.
Frank Hoenikker is the second child of Felix and Emily Hoenikker, Frank shows his father's lack of concern for others. A solitary child who tortures bugs and builds models, he disappears after his father's funeral, and is wanted by the FBI for being part of a stolen car ring. He buys himself a job as Major General on San Lorenzo by giving ice-nine to the island's dictator, Papa Monzano. Engaged to Mona Monzano and scheduled to be the next president of San Lorenzo, he talks Jonah into taking his place instead.
Felix Hoenikker’s youngest son, Newt, is a midget who flunked out of medical school at Cornell. He was briefly engaged to a Russian dancer, Zinka, a Russian spy who stole a chip of his ice-nine. He becomes an artist who paints meaningless and ugly pictures. Newt is Jonah’s fraternity brother, and is the main source of his information about the Hoenikker family.
Dr. Vox Humana
Dr. Vox Humana is an unorthodox Christian minister who studies in the States before returning to San Lorenzo. He comes to administer Papa Monzano’s last rites, but is turned away when Papa reveals he is a Bokononist
The Hundred Martyrs to Democracy
The Hundred Martyrs to Democracy were conscripted randomly from San Lorenzo and sent to fight for America after Pearl Harbor. A German submarine sank the ship in San Lorenzo's harbor, killing all of the soldiers. San Lorenzo created a national holiday in their memory.
Jack is the owner of the hobby shop where Frank Hoenikker worked in high school. He is proud of the work that Frank produced while he worked at the shop and has preserved it as a work of genius. He did not suspect that Frank was having an affair with his wife.
Lionel Boyd Johnson
Jonah is the narrator, whose first name is really John. He fittingly adopts the name of the prophet Jonah in the opening lines of the novel, since he is a reluctant witness of the evil around him, and his book a testimony to the last days of humans on earth. His plan to write a book about the day the atomic bomb was dropped on Hiroshima, titled The Day the World Ended, leads to his contact with Angela, Frank, and Newt Hoenikker. He becomes involved with their lives and their father Felix's scientific creation, ice-nine, the instrument for the end of the world. Jonah often tells the outrageous events as the straight man observer, allowing the bizarre characters to reveal their absurd lives in dialogue and action.
Lyman Ender Knowles
Lyman Ender Knowles is the black elevator operator at the Research Laboratory of the General Forge and Foundry Company. He seems to be crazy but speaks the truth, a type of “wise fool” pointing out that the scientists seemed to have lost something.
Krebbs is the artist whom Jonah let stay in his apartment when he traveled to Ilium. He was the wrang-wrang in Jonah's karass. When he wrecked Jonah's apartment and killed his cat, he turned Jonah away from nihilism and made him receptive to Bokononism.
Corporal Earl McCabe is a Marine deserter who befriends Lionel Johnson and the two wash ashore on the island of San Lorenzo. They use the principle of Dynamic Tension to create equilibrium in society where good and evil are recognizable. McCabe plays the evil dictator and Johnson plays the persecuted religious prophet, Bokonon. This role soon becomes too difficult for McCabe and he commits suicide.
Horlick and Claire Minton
The Mintons are the American ambassador to San Lorenzo and his wife, who tell Jonah about San Lorenzo on their flight to the island. They introduce Jonah to Philip Castle's book, which is his first contact with Bokononism. The Mintons are educated and intelligent but are a couple exemplifying a duprass, or closed group of two.
Mona Aamons Monzano
Mona Aamons Monzano is the daughter of the Finnish architect, Nestor Aamons, and an island woman, Celia. She is extremely beautiful and adopted by Papa Monzano. He adopted her to raise his popularity. The Books of Bokonon prophesized that Mona would marry the next president, and Mona was a devout Bokononist. Philip Castle and Jonah and most men are in love with her. Mona commits suicide by swallowing ice-nine with the rest of the population of San Lorenzo.
“Papa” Monzano is the dictator of San Lorenzo who employs Frank as Major General in exchange for ice-nine. He persecutes Bokononists and befriends Americans for their money. Monzano commits suicide by swallowing ice-nine, thus bringing on the end of the world.
Miss Pefko is a secretary at the research laboratoy in Ilium. She expresses dismay that she does not understand any of the research that is being done at the laboratory and exemplifies the uneducated masses with respect to science.
Stanley is Frank Hoenikker's servant on San Lorenzo.
Dr. Schlichter von Koenigswald
Dr. Schlichter Von Koenigswald is a physician who served with the S.S. in Germany for fourteen years, including six years at the concentration camp at Auschwitz. He works at Castle's hospital in San Lorenzo to make up for his past sins, and is Papa Monzano's doctor. He administers the Bokononist last rites to Papa. He is the second person to die of ice-nine, after Papa uses it to commit suicide.
Zinka is a Ukrainian midget ballet dancer who was briefly engaged to Newt. She is a Soviet spy who returns to her country after stealing ice-nine from Newt.