蔓越莓（英语：Cranberry），又称蔓越橘、小红莓，是杜鹃花科越橘属红莓苔子亚属（学名：拉丁语：Oxycoccus），又名毛蒿豆亚属的俗称，此亚属的物种均为常绿灌木，主要生长在北半球的清凉地带酸性泥炭土壤中。花深粉红色，总状花序。红色浆果可做水果食用。

目前在北美的一些地区被大量种植，收获的果实用来做成果汁、果酱等。蔓越莓酱（cranberry sauce）是美国感恩节主菜火鸡的传统配料。因为蔓越莓本身的酸味较强，作为饮料的果汁内一般兑有糖浆或苹果汁等较甜的成分。

近年来的研究发现，蔓越莓富含抗氧化的多酚类物质，适当服用有增强免疫系统、防止泌尿感染的作用。

Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus Oxycoccus of the genus Vaccinium. In Britain, cranberry may refer to the native species Vaccinium oxycoccos, while in North America, cranberry may refer to Vaccinium macrocarpon. Vaccinium oxycoccos is cultivated in central and northern Europe, while Vaccinium macrocarpon is cultivated throughout the northern United States, Canada and Chile. In some methods of classification, Oxycoccus is regarded as a genus in its own right. They can be found in acidic bogs throughout the cooler regions of the northern hemisphere.