'All I Want For Christmas Is You' is streamed millions of times around the world every festive season and has earned Mariah Carey more than £47 million in royalties.
Yet how much did fans of the catchy Christmas classic know the heartbreak and horror that lay behind it? Millions of couples around the world have no doubt sung it to each other as a romantic song but little did they know of the desperate unhappiness Mariah was feeling in her own marriage at the time - and that it wasn't her husband she'd written about.
She tied the knot with Sony Music CEO Tommy Mottola the year before the song's release, but later alleged in her memoir The Meaning of Mariah Carey that she was kept under lock and key and not allowed to leave their mansion on her own. Rather than it being a love song to her boyfriend, it was a sorrowful plea about reclaiming the free-spirited woman she had been before her troubled marriage.
Feeling that security guards and CCTV cameras followed her through her home, leaving her without privacy, she explained: "I created the fun and free girl in my videos so that I could watch a version of myself be alive." Mariah added: "[I wanted] to live vicariously through her - the girl I pretended to be, the girl I wished was me."
Though the track was a huge success and to this day remains the all-time best-selling Christmas single for a female artist, the dark backstory meant that, unbeknown to her fans, behind the scenes her relationship was falling apart. Mottola, who made a cameo appearance in the music video as Santa Claus, would confirm his divorce from her in 1998, after five years of marriage.
Her story is far from the only dark truth behind a Christmas classic: 'Santa Claus Is Coming To Town' is a staple song every winter season, seeming to play on repeat in just about every store shoppers enter to buy their gifts.
Yet as cheerful as the tune may sound, writer Haven Gillespie could scarcely bear to listen to it, as it reminded him of his brother's funeral which took place place just hours before he created the song.
Wham's Last Christmas could all too easily have ended in disaster after George Michael, apparently desperate to regain control after disputing his record contract, played every instrument heard on the song himself.
His sound engineer Chris Porter recalled him "cutting out" everyone and heading to the studio with a skeleton team, despite the fact “he wasn’t a musician [and] had no training on instruments at all".
Michael's risk paid off, as the song is still hugely popular today, making it to Christmas number one in 2023 and being predicted to reach the same heights this year too.
However, it was a time of great turbulence and turmoil for the then 21-year-old as he sought to assert his independence after struggles with music moguls.
He also faced being sued after it was argued that the song's melody sounded suspiciously similar to Barry Manilow's 'Can't Smile Without You', but the case was ultimately dismissed.
Then there was 'White Christmas', once certified the world's best-selling single of all time, which broke writer Irving Berlin's heart due to memories of his tragic son who'd died of Sudden Infant Death Syndrome on Christmas Day at just three weeks old.
'White Christmas' was also played on the Armed Forces Radio as a code signal for American soldiers to evacuate Saignon during the Vietnam war.
Homesick and heart-broken GIs had felt pangs of sorrow in their hearts when they heard the song, a painful reminder of how they'd been separated from their families during the special festive season.
Then there was another secretly war-focused tune, 'Do You Hear What I Hear?', which was most famously covered by Whitney Houston, and had a lyric about a "tail as big as a kite" in a nod to the Cuban Missile Crisis.
'Have Yourself A Merry Little Christmas' was originally written for the 1944 movie Meet Me In St Louis, but singer Judy Garland argued it was too "depressing".
There was a good reason for that, as its writer had been feeling melancholic about moving home when it was penned - and Frank Sinatra later requested for a lyric to be changed from "From now on, we'll have to muddle through somehow" to "Hang a shining star upon the highest bough".
These are just a few of the Christmas classics with a dark hidden history many party-goers never knew existed - and while they are a source of joy to many, for those who wrote and performed them, they were often harrowing.