Blackdown or Black Down may refer to:
Places
Australia
Blackdown, Queensland, a locality in the Central Highlands Region
Blackdown Tableland National Park in Queensland.
Canada
Blackdown Cadet Training Centre, a Canadian Cadet training centre (Tri-Force) located at CFB Borden, Ontario.
England
Blackdown, Dorset, a village near Chard
Black Down, Dorset, a hill near Portesham
Blackdown, Hampshire, a village near Winchester
Black Down, Somerset, a hill in the Mendip Hills
Blackdown, Warwickshire, a village near Leamington Spa
Blackdown, West Sussex, a hill also spelt Black Down
Blackdown Hill, Dorset, one of Dorset's highest points
Blackdown Hills, a range of hills in Somerset and Devon
Princess Royal Barracks, Deepcut (Blackdown Camp), a World War II army camp near Aldershot, Hampshire
Computing
Blackdown Java, a port of Sun's Java virtual machine to Linux.