He was a dark wizard, educated at Durmstrang, who developed a friendship with Albus Dumbledore when they were young, when Gellert was expelled from Durmstrang and staying with his great aunt, Bathilda Bagshot.
Dumbledore and Grindlewald soon become friends but after Dumbledore sister's death they never spoke again, until Dumbledore was forced to battle Grindlewald which resulted in Grindlewald being placed in prison and Dumbledore becoming the owner of the Elder Wand.
Gellert Grindewald was a dark wizard who Dumbledore had a legendary duel with in 1945 which led to Dumbledore winning and Grindewald being sent to Azkaban.
However we find out in the final book that they were also best friends when they were both 17, they used to fantasise about overpowering muggles. However a fight broke out beetween Gellert, Albus and his brother, Aberforth and it ended in the killing of Albus's sister. Gellert quickly fled and didn't meet Dumbledore again until the famous duel.
Gellert Grindlewald
Albus Dumbledore dueled Gellert Grindelwald to gain possession of the Elder Wand. He won that duel, Grindelwald was imprisoned, and Dumbledore kept the wand until his death.
yes, she was a squib and she had some disease or something that cause her to release a burst of magic when she became too stressed. Albus Dumbledore, Aberforth Dumbledore and Gellert Grindlewald were all dueling and Ariana became stressed and released magic which she died from.
Christian Fürchtegott Gellert died on December 13, 1769 at the age of 54.
He dies 
Gellert Grindlewald
Gellert Grindlewald, but mostly because he loved him and knew he would be rejected. Grindlewald also made him feel guilty about his sister's death.
Albus Dumbledore dueled Gellert Grindelwald to gain possession of the Elder Wand. He won that duel, Grindelwald was imprisoned, and Dumbledore kept the wand until his death.
Viktor Krum took offense at it during the Wedding of Bill and Fleur Weasley, because it was the symbol of the Deathly Hallows and believed to be the sign of Gellert Grindlewald (Krum was offended because Gellert killed Krum's grandfather)
Albus Dumbledore didn't marry anybody. He only ever loved one person in his life, Gellert Grindlewald. Together, Dumbledore and Grindlewald had plans to take over the wizarding world and control the muggles so that wizards could reveal themselves. However, Grindlewald was a lot more extreme with these plans than Dumbledore. One day, a fight between Albus, Gellert and Aberforth Dumbledore broke out which resulted in the death of Ariana Dumbledore. Either of the three men could have killed the girl. After this, Dumbledore didn't trust himself to take a position of power and never found love with anybody else. Besides, under British law gay people couldn't get married at the time the series was set.
He plays the part of Gellert Grindlewald- Dumbledore's childhood friend and companion when seeking the Deathly Hallows, Bathilda Bagshots nephew and also the thief that stole the elder wand from the wand-maker Gregorovitch. :)
yes, she was a squib and she had some disease or something that cause her to release a burst of magic when she became too stressed. Albus Dumbledore, Aberforth Dumbledore and Gellert Grindlewald were all dueling and Ariana became stressed and released magic which she died from.
Leon Gellert was born in 1892.
Leon Gellert died in 1977.
Gellert Tamas was born in 1963.
Lawrence Gellert died in 1979.
Lawrence Gellert was born in 1898.