Matthew Tyler Musto known professionally as Blackbear (stylised as blackbear), is an American hip hop recording artist, singer, songwriter, and record producer. He has collaborated with several musical artists such as Gnash, Justin Bieber, G-Eazy, Mike Posner, James Blake, Maejor Ali, Palisades, Machine Gun Kelly, Mod Sun, Rivers Cuomo, Childish Gambino, Pharrell Williams, and Linkin Park. He co-wrote "Boyfriend" by Justin Bieber, which debuted at number 2 on the Billboard Hot 100. He also produced the title track from G-Eazy's album 'These Things Happen'.

Source: Wikipedia