Brandon Stark (son of Willam)
From A Wiki of Ice and Fire
The World of Ice & Fire (appendix)|
A Game of Thrones (mentioned)
Brandon Stark was a member of House Stark, the only son of Lord Willam Stark and Lady Lyanne Glover. His mother died in childbirth, so Old Nan came to Winterfell to be his wet nurse. He died at age three of a summer chill.