David James "Dave" Mattacks (born 13 March 1948, Edgware, Middlesex, England) is a rock and folk drummer. Best known for his work with Fairport Convention, Mattacks has also worked both as a session musician, and as a performance artist. Apart from playing the drums he is also a versed keyboard player and occasionally played the bass guitar on studio recordings. He was with George Harrison when the news of John Lennon's murder came through.
He began as a trainee piano-tuner before taking up the drums. He played with several jazz bands before joining the electric folk band, Fairport Convention, in August 1969.