Rhinog Fach is a mountain in Snowdonia, North Wales and forms part of the Rhinogydd.

Technically, Rhinog Fach is a subsidiary summit of Y Llethr, but is a Marilyn.

To the north lies its higher cousin Rhinog Fawr, separated by the shapely pass of Bwlch Drws Ardudwy.

Although lower than the highest mountain in the Rhinog range, Y Llethr, it is often regarded as the true 'king of the Rhinogydd' due to its spectacular rocky peak.

Unlike Fach, Y Llethr's peak is grassy and unremarkable.