Steamboat Willie (1928) was the first movie of the cartoon Mickey Mouse distributed by Disney. Erroneously called "Steamhouse Willie" by some, it was revolutionary in its use of synchronized sound, which essentially ended the era of silent movies.
Disney's copyright in Mickey Mouse dates from this movie, which is scheduled to lose its copyright protection on January 1, 2024.
In October 1998, in an outrageous example of crony capitalism, Disney lobbied for and obtained a 20-year extension on this (and every other copyright) by persuading the House and the Senate to pass the Sonny Bono Copyright Extension Act (which critics of the bill dubbed ‘The Mickey Mouse Protection Act’) on the same day, which President Bill Clinton signed into law 20 days later. A legal challenge to the constitutionality of that law failed by a vote of 7-2 in the U.S. Supreme Court, in Eldred v. Ashcroft.