Matthew Grau, known professionally as Matt Ox, is an American rapper from Philadelphia. He rose to fame upon releasing his single "Overwhelming" in 2017, which has since reached nearly 30 million views on YouTube. He is best known for his feature on "$$$" with XXXTentacion released in March 2018, which has achieved nearly 100 million plays on Spotify. His debut album, OX, came out in October 2018.