Clan Ullek

The blue and white of the Ullek Clan (or the Ullekssons) is largely associated with Karaz-a-Karak - for that is the site of the clan’s settling and the runic symbol that appears, in one form or another, on all their banners. Ullek Redaxe was a thane beneath the first High King, Snorri Whitebeard, and his descendants still loyally support Thorgrim Grudgebearer. A prodigious line of stout-hearted folk, the many different factions of Clan Ullek use varied combinations of blue and white upon their shields and helms. Their war cry has been heard since the world was young.

Source
pg. 28
 * Warhammer Armies: Dwarfs (8th Edition)