The immigrant comic genius who would make America laugh through the Great Depression, Charlie Chaplin arrived in Hollywood in 1914, at the right moment in history to ride an emerging mass medium into immortality. Building from impoverished beginnings as a performer in English music halls, he combined slapstick and sentiment to become a great pantomime artist, able to conjure hilarious, disarming drunks; captivate with tenderness; or deliver a kick in the pants to the aristocracy without needing to utter a word.At Mack Sennett’s Keystone Studios, Chaplin combined ragged clothes and a waddling walk with a bowler hat and bottle-brush mustache to invent the Little Tramp. The character became a sensation — the screen’s first media and merchandising star — and Chaplin, who was writing, directing and starring in his films, became the most famous man in the world. Whether dining on boiled shoe in “The Gold Rush” or winning the heart of a blind flower girl in “City Lights,” Chaplin had a gift for creating images and scenarios that resonated across the social strata, and spanned some 70 films. In 1919, he banded with screen stars Douglas Fairbanks, Mary Pickford and director D.W. Griffith to form United Artists, challenging the studio stranglehold on cinema distribution and booking. But the coming of sound — against which Chaplin stubbornly held out through the making of his classic “Modern Times” in 1936 — diminished the magic of his art. Yet, 1939′s “The Great Dictator” directly challenged Hitler at the height of his power, and the Tramp lives on as a signature character in film.