The fictional character's name may have been derived from a jolly and flamboyant fireman named Tom Sawyer with whom Twain was acquainted in San Francisco, California, while Twain was employed as a reporter. Twain used to listen to Sawyer tell stories of his youth.

"Sam, he would listen to these pranks of mine with great interest and he'd occasionally take 'em down in his notebook. One day he says to me: 'I am going to put you between the covers of a book some of these days, Tom.' 'Go ahead, Sam,' I said, 'but don't disgrace my name.'"

Twain himself said the character sprang from three people, later identified as: John B. Briggs (who died in 1907), William Bowen (who died in 1893) and Twain, however Twain later changed his story saying Sawyer was fully formed solely from his imagination, but as Robert Graysmith says, "The great appropriator liked to pretend his characters sprang fully grown from his fertile mind."