- The narrator, a young writer.
- The hero, a reckless, energetic, womanizing young man from Colorado who has been in and out of jail.
- A good friend of Sal and Dean's, a brooding poet who is sensual and energetic.
- Dean's first wife, a pretty "dumb" blonde from Colorado.
- A tall, affable friend of Sal and Dean's. Not too bright, he'll do anything Dean says.
- Ed Dunkel's serious, disapproving newlywed wife.
- An old friend of Sal's from prep school. Remi, a flamboyant Frenchman, is a petty thief and gambler, constantly in debt but extravagant and sometimes gallant and generous.
- Remi Boncoeur's sulky girlfriend.
- She is tolerant, supportive, and kind. Sal lives at her house in Paterson, New Jersey, and Long Island. Throughout Sal's wanderings, she sends him money.
- Sal's friend from Denver; young, slim, blond and soft-spoken. He is interested in philosophy, anthropology, and pre-historic Indians.
- A friend of Sal's in Denver.
- A friend with whom Sal lives briefly in Denver. Major is a Hemingway-esque writer who is scornful of "arty" types but snobby himself, often talking to Sal about Europe and fine wines.
- Dean's second wife, for whom he divorces Marylou. Loyal Camille lives in San Francisco with her and Dean's children.
- Ray and Babe, brother and sister, Denver friends of Sal's group. Babe, "an enterprising blonde," is Tim Gray's girlfriend.
- A waitress in Denver whom Dean sets up with Sal. According to Dean, she has a "sex problem." Sal tries to prove to her that sex is beautiful, but he fails to impress her.
Old Bull Lee
- "Long, lean, strange and laconic," a long-time friend of Sal and Carlo, the teacher of their group. A traveler, writer, and junkie.
- A lost friend whom Sal and Dean seek everywhere they go.
- Bull Lee's sarcastic wife, a benzedrine junkie.
- A married woman in New York whom Sal wants to marry for awhile.
Denver D. Doll
- A Central City friend, whom Sal sees all over town. Eager Denver D. Doll shakes hands and makes sometimes-incoherent pleasantries ("Good afternoon" at midnight, "Happy New Year," etc.)--from morning to night, a caricature of an official.
- A pretty Mexican girl with whom Sal spends fifteen days in California. She comes from a family of grape-pickers in Sabinal, has a son, and is trying to escape a husband who beat her.
- Terry's wild, drunk, happy-go-lucky brother whom Sal meets in Sabinal.
- Terry and Rickey's friend, a manure-seller who smells like it. Big and eager to please, Ponzo is in love with Terry.
- Terry's seven-year-old son.
- Sal's friend in Tucson, Arizona; a shy writer who lives with his wife, baby, and mother.
- A friend of Dean's in San Francisco, Slim goes to jazz joints and adds the suffix "orooni" to everything he says.
- A friend of Sal's who chauffeurs Dean and Sal in San Francisco..
- Dean's third wife, a sexy brunette he meets in New York.
- An enthusiastic friend of Tim Gray's who goes to Mexico with Dean and Sal. Stan has a controlling grandfather he is trying to escape.
- The kind, polite Mexican man; Sal, Dean, and Stan's guide in Gregoria.