Royal fans are puzzled over the unusual nickname Prince William is said to use for his younger brother, Prince Harry.

Born on 15 September 1984, Harry was officially named Prince Henry Charles Albert David Wales by his parents, King Charles III, then the Prince of Wales, and Diana, Princess of Wales. From the beginning, however, Diana made it clear her son would be known as Harry. Over the years, the name stuck so firmly that many forget it is not his given name.

But Harry himself has claimed that William does not call him Henry or Harry — he calls him Harold. The question of why has sparked endless speculation.

The mystery was raised on Reddit when one user asked: “I’m listening to Spare, and [William] is always calling him Harold. His given name is Henry. Why?”

Many weighed in with their own theories. Some suggested that Harold was simply a sibling nickname, one that may have started in jest and evolved into something affectionate. Others were confused, pointing out that Harry is already a nickname, asking whether “a nickname can have its own nickname.”

For some, the logic hardly mattered. “It’s pretty funny when the legal version of someone’s name is shorter than the one it gets turned into,” one commenter said, comparing it to playful twists on names among friends. Harry himself once admitted to calling his brother “Willy,” which seems to support the idea that both brothers teased each other with exaggerated nicknames.

The first mention of Harold came to light in 2023, when The Guardian published an excerpt from Harry’s memoir Spare. In it, he recounted a heated argument with William, during which he alleged that his brother “grabbed him by the collar,” ripped his necklace, and knocked him to the floor. Harry wrote that William dismissed the altercation by saying: “I didn’t attack you, Harold.”

Harold, however, is far from Harry’s only nickname. Among friends he is known simply as “H,” while Meghan, Duchess of Sussex, prefers “Haz.” In 2023, Harry told Stephen Colbert on The Late Show that he has also been called Baz, Bazza, Spike, and even Bazzarooni. Meghan has shared that their son, Archie, calls his father “papa,” a name that also has royal echoes. King Charles once referred to his own father, Prince Philip, Duke of Edinburgh, as “my dear papa” in a heartfelt tribute following Philip’s death.

Whether Harold was meant as a brotherly joke or something more pointed, it has become one of the most curious details to emerge from Harry’s memoir — a reminder that even inside the most formal of families, nicknames carry their own stories.