William was the brother of Daniel Colter, who served as a stable boy for the noble Mills house. However, when William learns that his brother's relationship with Regina Mills has caused his death, he seeks vengeance and manages to confront Regina in the woods by stopping her carriage. He plans to use magical sand on Regina to stop her magic and make her defenseless, but before he can do so, Regina accidentally kills him.
- Daniel Colter (brother)
- Bk 3: "Out Of The Past" - Tea Party In March