When Guys and Dolls first premiered on Broadway, American audiences would have immediately recognized the language, style, and world made popular by celebrated author and journalist Damon Runyon.

Runyon wrote short stories celebrating the Broadway of New York's post-Prohibition era with a distinct style, now known as “Runyonesque”. His distinctive vernacular style is known as "Runyonese": a mixture of formal speech and colorful slang, almost always in present tense, and always devoid of contractions.

The Guys and Dolls musical was based on two of his stories, "The Idyll of Miss Sarah Brown" and "Blood Pressure", and borrows characters and story elements from a few other Runyon stories, including "Pick The Winner".

The author was born in 1884 as Alfred Damon Runyan. While writing for Pueblo’s Evening Press in his early teens, a printer misspelled his name as Runyon on one of his stories; he liked the change and it stuck.

At the age of 14, during the Spanish-American War, Runyon enlisted in the army and was sent to the Philippines. After being discharged in 1899, Runyon rode the rails home and later said that his experiences with hobos (homeless men who secretly rode in empty freight cars) marked the beginning of his interest in criminal lore and slang.

After a move to New York City and a job in the sports department of William Randolph Hearst’s New York American, he began writing his own column in 1914. By 1920, he had become so popular that he was able to write whatever he wanted in his column, which often featured human interest stories of sports, theatrical, and underworld characters of Broadway.

Runyon began writing short stories in 1920s featuring his Broadway characters with their distinctive dialects. Many of his stories were published in collections, the best known of which is Guys and Dolls. A remarkable number of these stories have been transferred to the stage and screen, the most famous being the musical Guys and Dolls (based on “The Idyll of Miss Sarah Brown”) and the Shirley Temple movie Little Miss Marker. In fact, one of Runyon’s best-remembered short stories, “Pick a Winner,” figured in the plot of four feature films.

Gambling, particularly on craps or horse races, was a common theme of Runyon's works, and he was a notorious gambler himself. He even ran a small stable of his own, and the Aqueduct Racetrack in Queens holds a thoroughbred horse race every year in honor of him.

Runyon died in 1946, and his ashes were scattered by airplane over Broadway in Manhattan. After his death due, the Damon Runyon Cancer Memorial Fund was created by fellow journalist Walter Winchell. The first-ever telethon was hosted by Milton Berle in 1949 to raise funds for the Damon Runyon Cancer Research Foundation.

(biographical information from the
Music Theatre International Guys and Dolls Study Guide and wikipedia.org)