Item from Harry Potter by J.K. Rowling
A tiny golden hourglass on a long chain that turns back time one hour per rotation, loaned to Hermione by the Ministry to attend overlapping classes and later used to save Sirius Black and Buckbeak the Hippogriff.
The Time-Turner is one of the most dangerous magical objects the Ministry casually loans to overachieving thirteen-year-olds. Hermione used it throughout her third year to attend every elective simultaneously, though the strain of living extra hours every day nearly broke her. The real crisis came when she and Harry used it to travel back three hours, save Buckbeak from execution, and rescue Sirius Black from the Dementor's Kiss — all without being seen by their past selves, because time travel in the Potterverse operates on a closed loop where everything you do in the past already happened. The entire stock of Time-Turners in the Department of Mysteries was destroyed during the Battle of the Department of Mysteries in Harry's fifth year, which conveniently eliminated the most plot-breaking magical device in the series.
A miniature golden hourglass hung on a fine gold chain long enough to loop around two people's necks. The hourglass is no larger than a walnut. Sand inside glows faintly. Each full rotation turns the user back one hour in time. The Ministry keeps them under strict regulation in the Department of Mysteries.
Also known as: Time-Turner, the Time-Turner, time turner