If you grew up playing with Barbie, chances are you assumed she didn't have a surname. After all, she's got by just fine with only one name since 1959.
However, fans were shocked when the brand recently announced that she does have one after all.
In honour of National Siblings Day on April 10, the Barbie account tweeted: "Happy #SiblingsDay, from the Roberts sisters!" alongside a photo of Barbie and her sisters.
Hundreds of users have commented and the post, which has been liked over 10,000 times.
A number of fans expressed their shock at the idea that Barbie had a surname.
However, according to the Evening Standard, this isn't the first time the name has been revaled.
Barbie creator Ruth Handler christened the doll Barbara Millicent Roberts after her own daughter of the same name, so it's always been there.
However, she quickly became known simply as "Barbie" — in keeping with other famous people like Madonna, Adele or Prince.
Despite her surname fading from common knowledge, there is even more backstory.
In 1960 a series of Random House novels revealed Barbie's parents' names were George and Michael Roberts. The family came from the fictional town of Willows, Wisconsin, where Barbie attended Willows High School.
Barbie's boyfriend, Ken, also reportedly has a surname.
The doll, introduced two years after Barbie, is apparently named Ken Carson.