Declan Costello (1 August 1926 – 6 June 2011) was an Irish judge, barrister and Fine Gael politician who served as President of the High Court from 1995 to 1998, a Judge of the High Court from 1977 to 1998 and Attorney General of Ireland from 1973 to 1977. He served as a Teachta Dála (TD) for the Dublin North-West constituency from 1951 to 1969 and for the Dublin South-West constituency from 1973 to 1977.