The most notable woman named Cecily Neville was the mother of Edward IV of England and Richard III of England (see below), but she was not the only one to bear that name.
Richard Neville, Earl of Warwick (known as "the Kingmaker") had a sister named Cecily Neville whose first husband became 1st Duke of Warwick (in 1445) and the only King of the Isle of Wight (and of Jersey and Guernsey) and whose second husband became 1st Earl of Worcester (in 1449), but little more is known of her.
Cecily Neville (3 May 1415 - 31 May 1495), Duchess of York, was called "the Rose of Raby" (because she was born at Raby Castle in Durham, England) and "Proud Cis" (because of her pride and a temper that went with it). Her mother was Joan Beaufort, grand-daughter of Edward III of England. Cecily married (in 1437) Richard (1411-1460), 3rd Duke of York, the leader of the Yorkists in the Wars of the Roses, and two of their sons became kings: Edward IV of England and Richard III of England. She was known for her piety as well as her pride.