blackthorn or sloe, low, spreading, thorny bush or small tree (Prunus spinosa) of the plum genus of the family Rosaceae (rose family), having black bark, white flowers, and deep blue fruits, usually rather acrid and not much larger than peas. Native to the Mediterranean area, the blackthorn is cultivated for hedges, its limbs are used in Ireland for canes and cudgels, and the juice of the berries is used in making brandy, sloe gin, and preserves and as a diluent of port. One of the hawthorns is sometimes called blackthorn. Blackthorn is classified in the division Magnoliophyta, class Magnoliopsida, order Rosales, family Rosaceae.

Blackthorn is a village and civil parish in the Cherwell district of Oxfordshire, England. It is situated close to the A41, the River Ray and the border with Buckinghamshire about four miles south-east of Bicester. According to the 2001 census it had a population of 267.

Blackthorn is roughly rectangular shaped. It is based around 4 roads - Station Road, Lower Road, Thame Road and Weir Lane.

Blackthorn once had (at various times) two public houses (The Rose & Crown, The Royal Oak), a butchers, a chapel, a primary school, a farm shop and a train station (which was where Smiths Concrete Limited is now situated).

Currently Blackthorn has a Village Hall and is home to a few small businesses. There is no public transport to Blackthorn. Blackthorn used to have a railway station on the Chiltern Line.

Blackthorn provides 2 or 3 events annually including the village fête, a summer barbecue and often another event (in the past this has included Halloween "trick or treating" and Christmas Carols). For the Queen's Jubilee it they had their own queen who paraded around the village in a dress. The Queen of blackthorn opened the fête and greeted everyone as they came in with a good kiss on the lips.

Harlan UK is based in Blackthorn and is occasionally the target of animal rights activists.

Neighbouring villages include Ambrosden, Arncott, Launton, Piddington and Marsh Gibbon.