JK Rowling reveals there were two Harry Potters

The first Harry Potter was a fierce defender of muggles

Fleamont and Euphemia lived long enough to see James marry a Muggle-born girl called Lily Evans, but not to meet their grandson, Harry. Dragon pox carried them off within days of each other, due to their advanced age, and James Potter then inherited Ignotus Peverell’s Invisibility Cloak.

J. K. Rowling seems to delight in dispensing new facts from the Harry Potter universe that drive fans to think about the series and its events differently, and the latest is an intriguing one.

Harry Potter himself is a messianic figure in the books and films, a chosen one. He wasn't, however, the first Harry Potter.

Rowling explained in a recent Pottermore entry:

"Henry Potter (Harry to his intimates), was a direct descendant of Hardwin and Iolanthe, and served on the Wizengamot from 1913 - 1921. Henry caused a minor stir when he publicly condemned then Minister for Magic, Archer Evermonde, who had forbidden the magical community to help Muggles waging the First World War. His outspokenness on the behalf of the Muggle community was also a strong contributing factor in the family’s exclusion from the ‘Sacred Twenty-Eight’."

Henry/Harry had a son named Fleamont who, alongside his wife Euphemia, "lived long enough to see James marry a Muggle-born girl called Lily Evans, but not to meet their grandson, Harry [the one we know]. Dragon pox carried them off within days of each other, due to their advanced age, and James Potter then inherited Ignotus Peverell’s Invisibility Cloak."

The original Harry Potter didn't make it into the books, but perhaps we'll see him in a future prequel, given how widely the franchise is now branching.