Question: Hap Hadley was a much sought-after pen-and-ink illustrator who created movie, circus and show billboards including which 1928 Charlie Chaplin film?

Context paragraphs:
Bill Ballantine (illustrator): Bill Ballantine (1910–1999) was a writer and illustrator of circus subjects, as well as a professional clown.  A prolific writer, Ballantine contributed circus and travel essays to major magazines.  His many stories of circus life appeared in "Collier's," "Holiday," "Harper’s Bazaar," "Saturday Evening Post," "True," "Saga", and "Seventeen."  Ballantine also authored ten books, including "Wild Tigers and Tame Fleas", "Horses and Their Bosses", and "Clown Alley", which chronicles his years as dean of the Ringling Bros. and Barnum & Bailey Clown College.  Over his long career as a writer/illustrator, he published nearly 100 articles on circus and travel and regularly illustrated "True" magazine's backpage feature “Strange but True” with his graceful and warmly humorous pen-and-ink line drawings.

Carpet sweeper: A carpet sweeper is a mechanical device for the cleaning of carpets.  They were popular before the introduction of the vacuum cleaner and have been largely superseded by them.  However, they continue to be used in many home and commercial applications because they are lightweight and quiet, enabling users to quickly clean small messes up from the floor without disturbing patrons, patients, babies and pets.  (A very early appearance in film occurs in the 1914 Charlie Chaplin film "Laughing Gas", where Chaplin uses it to clean the waiting-room floor of a dentist.)  Carpet sweepers are still available in many parts of the world.

Le bœuf sur le toit: Le Bœuf sur le toit, Op. 58 (English title, The Ox on the Roof: The Nothing-Doing Bar) is a surrealist ballet made on a score composed by Darius Milhaud, which was in turn strongly influenced by Brazilian popular music.  The title is that of an old Brazilian tango, one of close to 30 Brazilian tunes (choros) quoted in the composition.  The piece was originally to have been the score of a silent Charlie Chaplin film ("Cinéma-fantaisie" for violin and piano).

Charlie Chaplin: Sir Charles Spencer "Charlie" Chaplin, {'1': ", '2': ", '3': 'KBE', '4': "} (16 April 1889 – 25 December 1977) was an English comic actor, filmmaker, and composer who rose to fame in the era of silent film.  Chaplin became a worldwide icon through his screen persona "the Tramp" and is considered one of the most important figures in the history of the film industry.  His career spanned more than 75 years, from childhood in the Victorian era until a year before his death in 1977, and encompassed both adulation and controversy.

Marilyn Nash: Marilyn Nash ( Flint, Michigan October 26, 1926 – Oroville, California October 6, 2011).  Was an American actress and casting director.  She was best known for starring in the 1947 Charlie Chaplin film, "Monsieur Verdoux".

Triple Trouble (1918 film): Triple Trouble is a two-reel American silent comedy film that was released in 1918.  It starred Charlie Chaplin, Edna Purviance, and Leo White.  This film was not an official Chaplin film, even though it has many Chaplin directed scenes; it was edited together out of outtakes and newly shot footage by the Essanay Film Manufacturing Company, with Leo White as director for the new scenes.  Since Chaplin did not have legal control over the films made during his time with Essanay, he could not prevent its release.

Tillie's Punctured Romance (1928 film): Tillie's Punctured Romance is a lost 1928 American silent circus comedy film starring W. C. Fields as a ringmaster and Louise Fazenda as a runaway.  Written by Monte Brice and Keene Thompson and directed by A. Edward Sutherland, this movie has nothing to do with the revered 1914 Charles Chaplin film aside from sharing the same title.  However, Chester Conklin and Mack Swain appear in both films.

A Woman of the Sea: A Woman of the Sea, also known by its working title Sea Gulls, is an unreleased silent film produced in 1926 by the Chaplin Film Company.  It is one of only two lost Charlie Chaplin films (the other being "Her Friend the Bandit"), having been destroyed by Chaplin himself as a tax writeoff.

The Circus (film): The Circus is a 1928 silent film written and directed by Charlie Chaplin.  The film stars Chaplin, Al Ernest Garcia, Merna Kennedy, Harry Crocker, George Davis and Henry Bergman.  The ringmaster of an impoverished circus hires Chaplin's Little Tramp as a clown, but discovers that he can only be funny unintentionally, not on purpose.

Hap Hadley: Alvan Cordell "Hap" Hadley (March 16, 1895, Findlay, Illinois – August 4, 1976, Los Angeles, California) was an American artist specializing in pen and ink representations of popular subjects.  He created posters for various films, including Buster Keaton's "The General" (1926) and Charlie Chaplin's "The Circus" (1928), as well as promotional posters for the Ringling Bros. and Barnum & Bailey Circus and billboards for Roy Rogers.  A movie poster of "The General" was sold by Christie's East on December 5, 1994, for $46,000.

Supporting paragraphs: Hap Hadley Charlie Chaplin
Answer: The Circus