Cnemis or Knemis (Ancient Greek: Κνῆμις; Greek: Κνημίς) was either a range of mountains between the Cephissus Valley and the Gulf of Euboea combined with the Malian Gulf, or was a single mountain located in the northwest of that range.

The valley formed the heartland of Phocis, where the river originated, before entering Boeotia north of Orchomenos.

The uncertainty of what terrain was meant by "Cnemis" derives from the varying accounts of the many sources.

Mount Cnemis was a continuation of Callidromus, with which it was connected by a ridge, at the foot of which is the modern village of Mendenitsa.

The account of Cnemis in Smith, based on some of the ancient sources, seems to pinpoint the location of the populated mountain.