Knocknafenaig (Scottish Gaelic: Cnoc na Fennaig) is a ruined township on the Isle of Mull, Scotland.

Located in the south-western portion of the island known as the Ross of Mull, Knocknafenaig is an extremely well preserved township that shows many characteristics of the 19th-century and early 20th-century living conditions.

Although it is believed to have had medieval settlements, almost no evidence remains of these due to their organic nature.

The name Cnoc na Fennaig translates as "Hill of the Lazybeds" (this being a reference to the type of cultivation used throughout the area).

After the Highland Clearances and the Potato Famine in the mid-19th century the township became increasingly deserted.