Elder Wand

The Elder Wand is one of the Deathly Hallows. According to legend, whoever unites it with the Resurrection Stone and the Cloak of Invisibility will be the master of death. It is the most powerful wand that has ever existed. It was either made by the eldest of the three Peverell brothers, Antioch, or, according to legend, acquired by him from Death. It is enchanted so that whoever owns it will always win a duel. After killing a rival wizard in a duel shortly after obtaining the wand, Antioch drunkenly boasted of the wand's powers. He was murdered in his sleep that night, and another wizard took possession of the wand.

The Elder Wand is very powerful, and, as time went by, acquired names such as "The Deathstick" and the "Wand of Destiny." It eventually ended up in the ownership of the wandmaker Gregorovitch, who was trying to duplicate its powers. It was stolen from him by the dark wizard Grindelwald, who used it to cause havoc in Europe until he was defeated by Albus Dumbledore. The ownership of the wand then passed to him. Many years later, Severus Snape killed Dumbledore. This led Voldemort to believe ownership of the wand was Snape's, but Harry figured out it was actually Draco's because before Dumbledore died Draco had disarmed him and taken possesion of the wand (HBP P584). Nearly a year later, Harry disarmed Draco and unknowingly became the wand's master. When Voldemort used the Elder Wand to preform the Avada Kedavra curse on Harry, the curse rebounded on Voldemort, finally killing him, because Harry was the wand's master and therefore it wouldn't harm him.

Other elder wands
While "The Elder Wand" (capitalized) refers to one third of The Deathly Hallows, other wands have been made from elder wood. In general wizards seem to eschew elder wands, favoring wands made from various other woods, such as holly (Harry), or willow (Lily Evans and Ron). Ron repeats an old wizarding bromide, "Wand of elder, never prosper" after Hermione reads The Tale of the Three Brothers.