The Slayer, The Bringer of Death, The Life-Taker.
Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is Al-Mumeet (in Arabic: ٱلْمُمِيتُ), meaning the one who gives life and the one who takes it away. He ordains who will become lifeless. Eventually, we all return to Him.