Robert Siers Cavallo (born March 21, 1963) is an American record producer, musician, and record executive. He is among the biggest-selling producers in alternative music, having contributed to albums that have sold over 130 million units worldwide. He is also a three-time Grammy Award recipient. Primarily known for his production work with Green Day, he has also worked with Linkin Park, My Chemical Romance, Eric Clapton, Beth Hart, the Goo Goo Dolls, the Dave Matthews Band, Kid Rock, Jawbreaker, Alanis Morissette, Black Sabbath, Phil Collins, Paramore, Sixpence None the Richer, Lil Peep, ONE OK ROCK, Shinedown, Beauty School Dropout and Meat Loaf. Cavallo plays multiple instruments and has professional credits for his bass, keyboard, organ, piano, guitar and percussion work.