Mullacor (Irish: Mullaigh Mhór, meaning 'big hilltop') at 661 metres (2,169 ft), is an Irish mountain.

Mullacor is the 141st–highest peak in Ireland on the Arderin scale, and the 172nd–highest peak on the Vandeleur-Lynam scale. It's situated in the southern sector of the Wicklow Mountains range, and forms a broad horseshoe around the Upper Lake of the Glendalough valley with the mountains of Lugduff 652 metres (2,139 ft), Conavalla 734 metres (2,408 ft), the hydroelectric station at Turlough Hill 681 metres (2,234 ft), and Camaderry 699 metres (2,293 ft). Mullacor's western flank forms the step sides of the neighbouring Glenmalure valley. To the east of Mullacor is Cullentragh Mountain 510 metres (1,670 ft).

Mullacor's prominence of 102 metres (335 ft) does not qualify it as a Marilyn, but it does rank it as the 90th-highest mountain in Ireland on the MountainViews Online Database, 100 Highest Irish Mountains, where the minimum prominence threshold is 100 metres.

• Fairbairn, Helen (2014). Dublin & Wicklow: A Walking Guide. Collins Press. ISBN 978-1848892019.
• Fairbairn, Helen (2014). Ireland's Best Walks: A Walking Guide. Collins Press. ISBN 978-1848892118.
• MountainViews Online Database (Simon Stewart) (2013). A Guide to Ireland's Mountain Summits: The Vandeleur-Lynams & the Arderins. Collins Books. ISBN 978-1-84889-164-7.
• Dillion, Paddy (1993). The Mountains of Ireland: A Guide to Walking the Summits. Cicerone. ISBN 978-1852841102.

• Wicklow Way
• Wicklow Mountains
• Lists of mountains in Ireland
• List of mountains of the British Isles by height
• List of Hewitt mountains in England, Wales and Ireland

• MountainViews: The Irish Mountain Website, Mullacor
• MountainViews: Irish Online Mountain Database
• The Database of British and Irish Hills , the largest database of British Isles mountains ("DoBIH")
• Hill Bagging UK & Ireland, the searchable interface for the DoBIH