Knockboy (An Cnoc Buí in Irish, meaning Yellow Mountain) is a 706-metre-high mountain on the border between counties Cork and Kerry in Ireland.

Knockboy is the highest peak in the Shehy mountain range and the highest mountain in County Cork with its summit shared with County Kerry. It is the 104th highest peak in Ireland.

The mountain is composed of sandstone laid down in the Devonian period which was subsequently uplifted to form a mountain range, before being eroded into its present form by glaciers during the last ice age.

• List of Irish counties by highest point
• Lists of mountains in Ireland
• List of mountains of the British Isles by height
• List of P600 mountains in the British Isles
• List of Marilyns in the British Isles
• List of Hewitt mountains in England, Wales and Ireland

• Irish Walk Guides 1: South West. Seán Ó Súilleabháin, 1978.