This is an interesting one.. this song is a classic…. no birthday is ever complete without it.. so who wrote it? here is a take on this question from Yahoo
The timeless tune’s melody (aka the musical notes) was penned in the late 19th century by two sisters, Patty and Mildred Hill. Originally, the lyrics were different — instead of “happy birthday to you,” it was “good morning to all.” The sisters, both teachers, used their tune as a kind of classroom greeting.
As we learned from the urban legend experts at Snopes.com, nobody knows who wrote the words for “Happy Birthday to You.” In 1924, the lyrics were published in a songbook edited by Robert H. Coleman. First, they were just another verse. But eventually, thanks to radio and “talkie” movies, the birthday verse became its own ditty. Now it’s considered to be the best-known song in the world. And, irony of ironies, nobody knows who wrote it.
Before you start drawing comparisons to an unclaimed lottery ticket, know that people do collect royalties. Right now, the song’s rights belong to Warner Chappell Music, who remind you that if you sing their intellectual property in public, kindly mail them a check.