The Wizard of the month calendar on JKR.com has updated to reveal the new WotM for August 2007 to be…
Medieval (precise dates unknown).
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 image shows her wearing her diadem (tiara). This rounds out the Four Founders of Hogwarts, and also their “relics” from the story.