Cave people

"...everyone hates the Cave people."

- --Mance Rayder

The Cave people are a clan of Free Folk.

Season 3
The Cave people now march in the army of King-Beyond-the-Wall, Mance Rayder, who has united all of the different wildling clans to assault the Wall and force their passage to the south. Mance points out that it was difficult to unite the numerous different wildling clans into one army, as one clan is always feuding with another clan for one reason or another - Thenns against Hornfoots, Hornfoots against Ice-river clans - though everyone hates the cave people.

In the books
In the A Song of Ice and Fire novels,