I-Ignotus Peverell was one of the 3 brothers mentioned in The Tale of the Three Brothers in the book The Tales of Beedle the Bard which Hermione got in Dumbledore's will. He received the last of the Deathly Hallows, the Invisibility Cloak that Harry now owns considering that Ignotus is his ancestor.
According to legend, Ignotus was the youngest of the three Peverell brothers. Supposedly, the trio was out traveling one day when they came upon a treacherous river that had claimed many lives in its past when people tried to cross it. The three of them whipped out their wands and created a bridge to cross the river. Death, who was enraged that he had been cheated out of three new victims, appeared at the bridge's center and met the trio. He pretended to congratulate the three of them on their magical talent, offering each of them a prize. Antioch and Cadmus, Ignotus' two older brothers, asked respectively for an unbeatable wand and a stone that can bring people back from the dead. While their requests evidenced Antioch's desire for greater power and Cadmus' desire to further humiliate Death, Ignotus was the wisest of the three. Ignotus did not trust Death by any means, and rather than ask for something to further his own desires, he requested the power to leave that meeting without being followed by Death. Death, not wishing to betray any hint of his true intentions, begrudgingly took off his Invisibility Cloak and gave it to Ignotus. Ignotus' two brothers met terrible fates due to the murderous lust the Elder Wand created in wizards and the limitations of the Resurrection Stone. However, Ignotus used the Cloak of Invisibility to hide from Death, successfully eluding him for many years. Finally, when he was an old man and had lived a happy, long life, Ignotus took off the Cloak, passed it on to his son, and went with Death as an old friend, but on his own terms and not those of Death.
Interestingly enough, though not surprisingly, the word "Ignotus" is yet another of Rowling's uses of the Latin language. Meaning Unknown, the name is appropriate, for during the entire novel, many things are unknown to Harry, including his alleged relation to this Peverell. His descendants are Harry Potter's children James Sirius, Albus Severus and Lily Luna.
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