Rowena Ravenclaw

Rowena Ravenclawwas a witch noted for her cleverness and creativity, and was described by Xenophilius Lovegood as "beautiful." The Sorting Hat introduced her as “Fair Ravenclaw, from glen,” suggesting she was from Scotland. She was a good friend of Helga Hufflepuff; their friendship is used to emphasise the failed friendship between Godric Gryffindor and Salazar Slytherin. Ravenclaw devised the ever-changing floor plans and moving staircases in the Hogwarts castle, and coined the proverb "Wit beyond measure is man's greatest treasure."
Ravenclaw is described by the Sorting Hat as having selected students according to intelligence and wisdom. Ravenclaw House thus values in its members a sharp mind, wisdom, creativity, and cleverness for its own sake, and thus, rather than asking for a password from her members to get to the dormitories, a bronze eagle knocker asks them a riddle-like question which, if answered incorrectly, would force the student to wait until another could answer the question correctly, allowing the failed student to learn.
In Deathly Hallows, Harry learns that an artifact of Ravenclaw's became a Horcrux: her lost diadem, which granted enhanced wisdom to its wearer. Her daughter, Helena Ravenclaw (The Grey Lady) had once run away with it to surpass her mother in terms of intelligence and wisdom and hid it in Albania, in which its whereabouts remained unknown ever since. She, however, revealed its location to a young Tom Riddle, who proceeded to retrieve it and turn it into a Horcrux. In the original uncursed form, it is said to be able to imbue its wearer great wisdom. Late in her life, Rowena, suffering from a terminal illness, sent for the Bloody Baron to find her daughter so she could see her one last time before she died. However, Helena refused to go with the Baron, and he killed her in a paroxysm of rage. Immediately overcome with guilt, he then took his own life.
Ravenclaw was featured as Rowling's "Wizard of the Month" for August 2007. "One of the four famous Founders of Hogwarts School of Witchcraft and Wizardry, Rowena Ravenclaw was the most brilliant witch of her time, though legend has it that a broken heart - cause unknown - contributed to her early demise." Her Wizard of the Month status was cleverly revealed, for she appeared the month after the release of "Harry Potter and the Deathly Hallows", thus concealing what possible Horcrux item she possessed until after the book's release.
Rowena is a Latinised form of an old Germanic name. The elements in the name mean "Fame," (cf. the Anglo-Saxon hrōd, or hrōð), and "Joy," (cf. the Anglo-Saxon wyn(n)), or "Friend," (cf. the Anglo-Saxon wine). Rowena, Queen of Britain is a figure in Britain's traditional history; she was supposedly the daughter of Hengest and the wife of Vortigern.