Rhosddu (Welsh: Rhos-ddu; Welsh pronunciation^ⓘ) is a suburb and community in Wrexham County Borough, Wales, covering the north-western parts of the city of Wrexham and comprises the wards of Grosvenor, Garden Village and Stansty.

At the 2011 Census, the population of the community was 6,840 and 11.8% of people aged 3+ spoke Welsh.

Rhosddu was formed as a new ecclesiastical parish by an Order in Council in 1886. The parish contained the townships of Acton, Bieston and Gourton (from the parish of Wrexham), the township of Borras Riffri (from the parish of Gresford), and the township of Stansty (from the parish of Gwersyllt). In 1972, Rhosddu reverted to the parish of Wrexham.

Rhosddu was in the civil parish of Stansty until 1935, when it was absorbed into the municipal borough of Wrexham. The borough was abolished in 1974, under the terms of the Local Government Act 1972. A community called Rhosddu was subsequently created in 1985 as one of four communities of Wrexham Maelor within the area of the pre-1974 borough of Wrexham (Rhosddu, Offa, Caia Park, and Acton).

The name Rhosddu is formed on the Welsh words rhos, "moor" or "rush pasture", and ddu, "black". The name may derive from the presence of coal and peat below the poorly drained surface as evidenced by old field names in the neighbouring Stansty area which indicate similar features e.g. 'Tirodd Duon' (black lands). It is likely that the area was common land in medieval times used by tenants of the manor as rough pasture for cattle grazing. Rhosddu Farm (also known as Walnut Tree Farm) was first recorded in 1762 in the possession of the Griffiths family and was located on the site of the Walnut Tree public house on New Road.

The first housing developments in the Rhosddu area began from 1856 following the arrival of the railway and the location of associated goods and carriage sheds in the area. The population increased further as a result of the Wrexham and Action Colliery which opened in the late 1860s.

St James' church was built in Cefn sandstone to designs by W. Turner of Wrexham. The foundation was laid on 30 September 1874 and it was opened for worship in January 1876, although it was not consecrated until 27 April 1886. The church is now a Grade II Listed building, being considered a good example of a late 19th-century church retaining many original features.

Rhosddu School (originally known as Stansty Park Board School) opened in 1877 and moved into its current premises on Price's Lane in 1915.