Isley (イースレイ, Īsurei) is a former male Claymore with long, silver hair, hence his nickname "White Silver King". Isley was Claymore #1 among the first generation of Claymores. Upon Awakening, he took control of the Northern lands, but later gave them up in favor of the South. He is the lover of Priscilla. Despite being an Awakened being for more than 78 generations, Isley still remembers almost everything he ever learned about swordsmanship.
Most people believe that Isley defeated Priscilla when she went on a rampage in the North and made her his lover. However, this was later proven untrue - despite initially holding the upper hand, Isley had nearly half his torso torn off by Priscilla, who in contrast regenerated from her injuries at phenomenal speed. For unknown reasons, Priscilla suddenly reverted back to her human form in the midst of battle. Realizing that her Awakening had caused her mind to regress, Isley responded by returning to his human form as well, and swore allegiance to Priscilla. His exact motivations remain unknown.
Isley went on to amass an army of Awakened, raising a total of 31 soldiers, including the former #2 Rigardo. In response, the Claymore organisation dispatched two dozen warriors to delay what they feared was an attempt at expansion. After defeating all 24 Claymores, Isley then split his troops, sending half against the Claymore headquarters and the remainder against Abyssal One Riful. With the Claymores #1 through 3 and Riful thus occupied, Isley moved against Luciela of the South, defeating her. It is later revealed that his intentions were two-fold; by killing Luciela, Isley eliminated the possibility of a team-up between her and Riful, which would have been the only possible way to defeat Priscilla. This effectively made Isley and Priscilla the single most powerful faction. Conquering Luciela's lands also ensured that Isley fulfilled his promise to Priscilla, namely to take her to the South to find her parents.
During the Northern campaign, Isley found Raki and took him in. Later, Isley agrees to become Raki's teacher and begins to instruct him in swordsmanship, commenting that Raki reminds him a lot of how he was in his own youth. Isley now resides in his newly conquered territory of the south with Priscilla. While he has pledged his life to the more powerful Priscilla, he is far more intelligent and experienced than she is and often seems to be the dominant and active member of their partnership.