He was an unnamed shape shifter. When Link, the boy from Kokiri Forest, came along, He turned himself into his new form, commonly known as Dark Link. When Link turned into an adult, so did Dark Link
Slice! Dark Link gave Link a huge gash. He fell to the floor in pain. A bottled fairy revived him. It was a long and weary battle, and eventually Link won. Hmmph. What an over achiever, Link thought, trying to beat ME.