Gellert Grindelwald (c. 1882/1883 – March 1998) was a Dark wizard who was considered to be amongst the most powerful and notorious wizards of all time, his only superiors being Albus Dumbledore and Lord Voldemort.A student at Durmstrang Institute, Grindelwald was expelled for twisted, dark experiments and near-fatal attacks on students.

After leaving Durmstrang, he fostered a romantic relationship with a young Albus Dumbledore, making plans to find the Deathly Hallows and lead a Wizarding revolution to end the International Statute of Secrecy, and create a new wizard-led order that would dominate Muggles. At seventeen, their partnership fell apart after the two were involved in a three-way duel with Dumbledore's brother Aberforth that resulted in the death of Dumbledore's sister Ariana. Grindelwald left Britain and later stole the Elder Wand from Mykew Gregorovitch, proceeding alone with the revolution he and Dumbledore had planned.

Grindelwald was a complex figure, highly idealistic and talented, dedicated to achieve his ends at any cost. A revolutionary operating outside the law, he and his followers committed numerous crimes, including several murders. With violent acts in both the United States and Europe, Grindelwald ultimately established a power base at Nurmengard Castle in Austria. In 1945, at the height of Grindelwald's power, Dumbledore confronted and defeated him in a legendary duel. He was subsequently imprisoned in his own fortress for decades, and was finally slain there by Lord Voldemort in 1998 when he refused to give up the location of the Elder Wand.