Godelot was an early medieval Dark wizard, who was an owner of the Elder Wand and the author of Magick Moste Evile (TBB/TTB, DH21).
Godelot lived in the middle of the first millennium, before the founding of Hogwarts and a century after the previous appearance of the wand in history, when it was owned by Emeric the Evil and taken by Egbert the Egregious (TBB).
He wrote about the Elder Wand almost as though it was a sentient being, describing it as his "moste wicked and subtle friend... who knowes ways of magick moste evile". This phrase later became the title of his masterpiece, which he claimed the wand had helped him write (TBB).
Godelot died after being locked in his own cellar by his son Hereward, who took the Elder Wand (TBB/TTB, DH21).