Emer Anne Costello (née Malone; born 3 September 1962) is an Irish former Labour Party politician who served as a Member of the European Parliament (MEP) for the Dublin constituency from 2012 to 2014, Lord Mayor of Dublin from 2009 to 2010 and a Dublin City Councillor for the North Inner City area from 2003 to 2012.

She was first co-opted onto Dublin City Council as a member for the North Inner City area in 2003 to replace her husband, Joe Costello, who resigned following the end of the dual mandate.

[1] She was elected Lord Mayor of Dublin by a unanimous vote of the city council at its annual meeting on 15 June 2009, with the support of Fine Gael and the Green Party.

[2] Costello has observed international elections in Cambodia, South Africa and Bosnia and Herzegovina.

[4] Costello replaced Proinsias De Rossa in the European Parliament when he resigned as an MEP in February 2012.