House Clegane is a house of landed knights in the westerlands. They hold fealty to House Lannister of Casterly Rock, and are among their primary bannermen. Their lands are southeast of the Rock and include a towerhouse, which, according to a semi-canon source, is named Clegane's Keep. Their sigil depicts three dogs on a yellow field.
The first knight of House Clegane was kennelmaster at Casterly Rock. During one autumn year he saved Lord Tytos Lannister from a lioness, although he lost a leg and three dogs while doing so. Lord Tytos rewarded him with lands and a towerhouse. Ser Clegane's son was placed in Tytos's service as his squire. For his sigil Ser Clegane used the three dogs he lost saving Tytos, on the yellow of autumn grass.
The kennelmaster's son, the father of Gregor and Sandor, died in a hunting accident. Their sister died young under queer circumstances. Gregor is known for his unspeakable cruelty; this is mirrored in the Mountain's men, who casually commit atrocities during their campaigns. Sandor was driven away by this behavior, taking service with House Lannister and refusing to take a knight's vows to avoid association with his elder.
Gregor was knighted by Prince Rhaegar Targaryen, the heir of King Aerys II Targaryen. During the Sack of King's Landing, Gregor murdered Rhaegar's son, the infant Prince Aegon Targaryen, before raping and murdering his mother and Rhaegar's bride, Princess Elia Martell.
The known Bettleys during the timespan of the events described in A Song of Ice and Fire are:
Ser Jon Bettley, known as Beardless Jon.
His homely wife.