"My Happy Ending" is a song written and produced by Avril Lavigne and Butch Walker, and engineered by Russ T. Cobb for Lavigne's second album, Under My Skin (2004). It was released as the album's second internationally released single in 2004 and became Lavigne's fourth most successful single. It peaked higher than "Don't Tell Me", the album's first single. In the United Kingdom, it reached the top five; in the United States, it peaked at number nine (staying in #9 for 4 weeks), doing better in Mexico where it peaked at number 1. Structurally, the song is written in 4/4 style and has a repeated hook in both the chorus and in the intro and outro.

The RIAA certified "My Happy Ending" platinum in January 2005, making it Lavigne's second platinum single after "I'm With You" (2002). Allmusic highlighted the song as one of the most significative post-grunge songs of all time.

A happy ending is an ending of the plot of a work of fiction in which almost everything turns out for the best for the protagonists, their sidekicks, and almost everyone except the villains.

In storylines where the protagonists are in physical danger, a happy ending would mainly consist in their surviving and successfully concluding their quest or mission; where there is no physical danger, a happy ending is often defined as lovers consummating their love despite various factors which may have thwarted it; and a considerable number of storylines combine both factors.

A Times review of The Spy Who Came in from the Cold strongly criticised John le Carré for failing to provide a happy ending, and gave unequivocal reasons why in the reviewer's opinion (shared by many others) such an ending is needed: "The hero must triumph over his enemies, as surely as Jack must kill the giant in the nursery tale. If the giant kills Jack, we have missed the whole point of the story."

A happy ending is epitomized in the standard fairy tale ending phrase, "happily ever after" or "and they lived happily ever after." (One Thousand and One Nights has the more restrained formula they lived happily until there came to them the One who Destroys all Happiness (i.e. Death)). Satisfactory happy endings are happy for the reader as well, in that the characters he or she sympathizes with are rewarded. However, some consider this as not an ending, but an open path for a possible sequel. For example, at the end of The Lion King, Simba defeats Scar, becomes king, marries and has a daughter, Kiara, thus giving way to The Lion King II: Simba's Pride.

Avril Ramona Lavigne (pronunciation: /ˈævrɨl ləˈviːn/; AV-ril lə-VEEN; born 27 September 1984) is a Canadian singer-songwriter. She was born in Belleville, Ontario, but spent most of her youth in the small town of Napanee. By the age of 15, she had appeared on stage with Shania Twain; by 16, she had signed a two-album recording contract with Arista Records worth more than $2 million. In 2002, when she was 17 years old, Lavigne broke onto the music scene with her debut album Let Go.

Let Go made Lavigne the youngest female soloist to reach No. 1 in the UK, and the album was certified four-times platinum by the Recording Industry Association of America. By 2009, over 16 million copies had been sold worldwide. Her breakthrough single, "Complicated", peaked at No. 1 in many countries around the world, as did the album Let Go. Her second album, Under My Skin, was released in 2004 and was her first album to peak at No. 1 on the U.S. Billboard 200, eventually selling more than 10 million copies worldwide. The Best Damn Thing, Lavigne’s third album, was released in 2007, becoming her third No. 1 album in the UK Albums Chart and featuring her first U.S. Billboard Hot 100 No. 1 single, "Girlfriend". Lavigne has scored six number-one singles worldwide, including "Complicated", "Sk8er Boi", "I'm with You", "My Happy Ending", "Nobody's Home", and "Girlfriend". With more than 30 million copies of her albums sold worldwide, Lavigne is one of the top-selling artists releasing albums in the U.S., with over 10.25 million copies certified by the RIAA. Her fourth studio album, Goodbye Lullaby, was released in March 2011. Goodbye Lullaby gave Lavigne her fourth top 10 album on the U.S. Billboard 200 and the UK Albums Chart and her third No. 1 album in both Japan and Australia. Three months after the release of Goodbye Lullaby, Lavigne began work on her fifth album, which will be released on Epic Records following her departure from RCA Records.