The copyright to "Happy Birthday" is owned by Warner/Chappell Music. The song, which originated as "Good Morning to You," was written by sisters Mildred and Patty Hill in the late 19th century.
Some people have questioned the validity of the copyright to "Happy Birthday." Law professor Robert Brauneis claims that, because there is no concrete evidence the Hill sisters wrote the "Happy Birthday" variation of their original song, the copyright on "Happy Birthday" is unenforceable. Regardless, many movies and TV shows will use an original song, rather than possibly pay to use "Happy Birthday."
As of 2015, the song reportedly earns Warner/Chappell Music over $2 million per year in royalties.