Kreacher is the house-elf who serves the Black family in the Harry Potter books.
Kreacher lives at 12 Grimmauld Place, the ancestral home of Sirius Black. He is fiercely loyal to the pure-blood Black family’s ideals, especially those of Walburga Black, and initially treats Sirius and his friends with contempt.
After Sirius’s death, Kreacher becomes important to the Horcrux hunt. Harry discovers that Kreacher had been ordered to help Mundungus Fletcher and later leads the elf toward the locket Horcrux. Kreacher keeps the locket for years before giving it to Regulus Black.
Kreacher is often confused with Dobby, who serves the Malfoy family before becoming Harry’s ally. Winky serves the Crouch family.