Iron Maiden named itself after a torture device that probably never tortured anyone in the Middle Ages.
The band formed in 1975 in Leyton, East London, led by bassist Steve Harris. He had just left an earlier group, Smiler. According to Wikipedia, the idea came from a film adaptation of Alexandre Dumas's The Man in the Iron Mask. The title reminded him of the iron maiden, and the name followed. The band also considered "Ash Mountain."
The device is the stranger half of the story. An iron maiden is an upright cabinet, shaped roughly like a person, lined with spikes inside. The victim was said to be shut in and pierced. In German it is the Eiserne Jungfrau, the "iron virgin."
The trouble is the paper trail. Live Science says the first historical reference came long after the Middle Ages, in the late 1700s. The German writer Johann Philipp Siebenkees described an execution by iron maiden in Nuremberg in 1515. Wikipedia says historians have questioned his account.
The famous examples are also suspect. The Iron Maiden of Nuremberg was put together around the early 1800s, and it was destroyed in Allied bombing during the Second World War. Scholars cited by Wikipedia argue that such objects were assembled from museum pieces to make spectacular exhibits.
The idea may have grown from something real but less deadly. Wikipedia points to the Schandmantel, or "cloak of shame," a medieval punishment made of wood and metal but without spikes. Live Science quotes the historian Peter Konieczny on how people of the 1700s and 1800s exaggerated the brutality of the past.
None of that has hurt the name. Wikipedia says the band has sold more than 130 million albums. Its mascot, Eddie, was created by artist Derek Riggs around 1979 and 1980.
So a heavy metal band took its name from a piece of heavy metal with a shaky history. The myth is older than the band, but not by as much as the museums once claimed.