Mountcastle may refer to:
Places Mountcastle, Edinburgh, a suburb of the Scottish city Mountcastle, County Tyrone, a townland in County Tyrone, Northern Ireland Mountcastle, Virginia, an unincorporated community in New Kent County, Virginia Mountcastle, Dublin, hamlet which is now incorporated into the Irish capital city
People Clara Mountcastle (1837–1908), Canadian author and artist Robert Edward Lee Mountcastle (1865–1913), American lawyer and politician Ryan Mountcastle (born 1997), American baseball player Vernon Benjamin Mountcastle (1918–2015), neuroscientist from the Johns Hopkins University
See also Duke of Abercorn, the 6th earl was also created Baron Mountcastle and Viscount Strabane, in the Peerage of Ireland