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 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, with whom he worked on and off until 1997. In 1998, he moved to Marblehead, Massachusetts, United States, where he is a sought-after studio musician, record producer, and member of the band Super Genius, while still touring regularly with various acts in the UK, Europe and Australia.
He replaced Martin Lamble, who had died on 12 May 1969 in a road accident on the M1 motorway. Mattacks left Fairport Convention in early 1972 to join The Albion Country Band. Meanwhile he had also contributed to numerous studio recordings such as the Morris On project, Nick Drake's Bryter Layter, Steve Ashley's "Stroll On" sessions, Steeleye Span's debut album Hark! The Village Wait, John Martyn's Solid Air and Harvey Andrews' album Writer of Songs. He returned to Fairport Convention in order to help complete the 1973 album Rosie with a revamped line up of the band.