Cabra (Irish: An Chabrach, meaning "the poor land") is a suburb on the northside of Dublin city in Ireland. It is approximately 2 kilometres (1.2 mi) northwest of the city centre, in the administrative area of Dublin City Council. It was commonly known as Cabragh until the early 20th century.

From about 1480, the manor of Cabra was held by a branch of the Plunket family, later ennobled as Earls of Fingall, whose main residence was Dunsoghly Castle near Finglas.

There are three contiguous townlands called "Cabra", each in a different civil parish: Castleknock, Glasnevin and Grangegorman. The three met at the gate lodge of "Cabragh House", which is today the situation of the roundabout at the junction of Ratoath Road and Drumcliffe Road. "Cabragh House" was located where the current Canon Burke Senior Citizens Flats complex stands. Completed in 1598, it was first occupied by the Seagrave Family, who could trace their linage back to the Viking invasion of Ireland. The mansion was the home of the hanging judge Lord Norbery until he died in 1831 and, unusually for Catholics at the time, the Seagrave family managed to acquire it again. Charles Segrave, whose son was the famous racing driver Henry Segrave, who was the first person to hold both the land and water speed records simultaneously, lived there until 1912. The big house was bought by Dublin Corporation by way of a CPO in 1939 for the construction of local authority housing and the historic house was razed to the ground.

For hundreds of years the area mostly comprised fields and open countryside on the edge of the city. It was not until the 1920s that large scale housing developments took place. Many of the people who moved to the new suburb were from the rooms and tenement buildings of the city centre.

Quarry Road was originally called Quarry Lane after a small quarry which was situated near where the current statue of Our Blessed Lady is located at the roundabout with Fassaugh Road (which originally was called Fassaugh Lane.) This quarry was filled in the early part of the 1900s and the family who lived in the Homestead grew cabbages on the reclaimed land.

The Industrial Revolution brought the construction of the Royal Canal in 1790 and the laying of the Dublin-Galway railway line of which both went through the heart of the area. From about 1880-1930, Cabra was a prominent market garden centre and a giant lairage, where cattle being brought to market at Hanlon's Corner were kept in pens and grazing fields.

The Roman Catholic church of Christ the King was built during the years following the Eucumenical Congress of 1932. It seemed appropriate to employ John J. Robinson of Robinson and Keefe to design the new church, as he had been Architect for all the structures (Phoenix Park, Merrion Road, O'Connell bridge etc.) built for the Congress. The church which is cross shaped in plan was built in red brick with a huge statue of Christ integrated into the tower which is on the axis of the approach road. An Architect's perspective drawing of the church exists in the Irish Architectural Archive in Merrion Square. This church shares many features with St. Therese Mount Merrion which was built by the same Architect some 20 years later. Robinson is also famed as being Architect to Galway Cathedral.

Broom Bridge, also known as Brougham Bridge, is a small bridge along Broombridge Road which crosses the Royal Canal in Cabra. The bridge is named after William Broom, one of the directors of the Royal Canal company. Broom Bridge is the location where Sir William Rowan Hamilton, following a 'eureka experience', first wrote down the fundamental formula for quaternions on 16 October 1843, which is to this day commemorated by a stone plaque on the northwest corner of the underside of the bridge. The text on the plaque reads:
“Here as he walked by on the 16th of October 1843 Sir William Rowan Hamilton in a flash of genius discovered the fundamental formula for quaternion multiplication i² = j² = k² = ijk = −1 and cut it on a stone of this bridge.”
Given the historical importance of the mathematical contribution, mathematicians have been known to make a pilgrimage of sorts to the site.