Famously, the original Steamboat Willie version of Mickey Mouse entered the public domain last year, and people everywhere (including us) had some fun with his likeness. Pieces of intellectual property lose their copyright protection after 95 years, and with the new year comes a whole bunch of new material in the public domain, including a bunch of popular standards from 1929.
As explained in this piece from Duke University, Arthur Freed and Nacio Herb Brown's "Singin' in the Rain" (for 1929's Broadway's Hollywood Music Box Revue), also appeared in the movie The Hollywood Revue of 1929 that same year. Both the song and the film are now in the public domain. Other now-public 1929 songs include Fats Waller, Harry Brooks and Andy Paul Razaf's "Ain't Misbehavin'" and "(What Did I Do to Be So) Black and Blue," plus George Gershwin's "An American in Paris," Maurice Ravel's "Boléro," Alfred Dubin and Joseph Burke's "Tiptoe Through the Tulips" (that's not the Tiny Tim version, just to be clear), Jack Yellen and Milton Ager's "Happy Days Are Here Again," Cole Porter's "What Is This Thing Called Love?" and Jimmie Rodgers's "Waiting for a Train."
It should be noted that those compositions specifically are now public domain, but any alternate recording of the songs (like the Tiny Tim Version of "Tulips" or Louis Armstrong's 1929 recording of "Ain't Misbehavin'") are not. Actual sound recordings take 100 years to enter the public domain, so this year's crop of new public domain tunes come from 1924, like Gershwin's "Rhapsody in Blue," Marian Anderson's "My Way's Cloudy," Al Jolson's "California Here I Come," Jelly Roll Morton's (not to be confused with Jelly Roll) "Shreveport Stomp" and the version of "Krooked Blues" recorded by Louis Armstrong with King Oliver's Creole Jazz Band.
Alongside the music, other new public art includes books like Ernest Hemingway's A Farewell to Arms, William Faulkner's The Sound and the Fury, Virginia Woolf's A Room of One's Own and Dashiell Hammett's The Maltese Falcon and Red Harvest, plus films like Gold Diggers of Broadway, The Broadway Melody, the Marx Brothers' The Cocoanuts, John Ford's The Black Watch and Alfred Hitchcock's Blackmail.
The original versions of the characters Popeye and Tintin are also now free to use. You can read the whole Duke piece here.