The Deathly Hallows are three sacred objects given to the three Peverell brothers by Death himself. The three objects are an undefeatable wand (the Elder wand), a cloak that hides you from death (the Invisibility Cloak), and a stone with the power to resurrect the dead (the Resurrection Stone). When one possesses all three objects at a time, he or she will become a master of death.
That's the tale from Beddle. But the powerful wizards themselves were the likely creators of these objects. Antioch Peverell's Elder Wand was the most powerful wand ever made but obviously not undefeatable or it would not have been taken so many times. Dumbledore defeated Grindelwald in a duel to capture it. Harry Potter had inherited the Cloak of Invisibility, passed down through centuries from Ignotus Peverell. He used it extensively, especially in the books. And Cadmus Peverell's Resurrection Stone had been set in a gold ring and handed down to Marvolo Gaunt, Tom Riddle's grandfather. He stole it from his uncle, Morfin Gaunt, and made it into a horcrux, unaware of the stone's power to recall dead loved ones. Though they could be seen and talked to, they were not of this world. Voldemort wouldn't have had a use for that anyway as he had no loved ones, living or dead.