On the summit is an ancient burial cairn, with a natural rocky outcrop on its east side forming the appearance of a doorway.

Fionn stood atop the mountain and declared that whichever woman won a footrace to the top would be his wife.

[2] Irish folklore holds that it is bad luck to damage or disrespect such tombs and that deliberately doing so could bring a curse.

In one tale, Fionn and his men are cooking a pig on the banks of the River Suir when an Otherworld being called Cúldubh comes out of the cairn on Slievenamon and snatches it.

[8] In Acallam na Senórach (Dialogue of the Elders), Fionn, Caílte and other members of the fianna chase a fawn to Slievenamon.

It is also mentioned in the books The Hidden Side of Things (1913) and The Lives of Alcyone (1924, with Annie Besant) written by the theosophist clairvoyant Charles Webster Leadbeater.

In it, Big Man chases a deer into a cave and falls asleep for 200 years to awaken in a time when he is a giant among men.

Slievenamon was escorting the army's commander-in-chief, Michael Collins, when he was ambushed and killed near Béal na Bláth.