David James "Dave" Mattacks (born 13 March 1948, Edgware, Middlesex, England) is an English 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.