Gregory Allen Kurstin (born May 14, 1969) is an American record producer, multi-instrumentalist, and songwriter. He has won nine Grammy Awards, including Producer of the Year, Non-Classical in 2017 and 2018, and written and produced four songs that hit #1 on the Billboard Hot 100.Kurstin collaborated with Adele on the albums 25 and 30. He co-wrote and produced "Easy on Me," the first single from 30, which hit the US Hot 100 only five hours after its release and broke all-time records on Spotify with 24 million plays within the first 24 hours it was available. He also co-wrote, produced and played most of the instruments on Adele's record-breaking 2015 single "Hello". Among others, he has worked with Sia, Kelly Clarkson, Halsey, Maren Morris, Beck, Paul McCartney, Pink, Lily Allen, Harry Styles, and the Foo Fighters. He often plays guitar, bass, keyboards and drums, and engineers and programs the records he produces.Kurstin began his career as a jazz pianist and later co-founded Geggy Tah. He has collaborated with Inara George in the Bird and the Bee since 2004.

Source: Wikipedia (https://en.wikipedia.org/wiki/Greg_Kurstin)