Tall William is the eldest son of Old William and the older brother to William the Almost Youngest and William the Absolute Youngest. He towers over the other children and acts as a older brother to them. In E. Aster Bunnymund and the Warrior Eggs at the Earth's Core! Tall William did his best to look after the other children and break out of their cages until North and the others came to their rescue.
Tall William is very protective of his two younger brothers and all the other children in Santoff Claussen. He is very level headed and quick to react to danger, putting himself between his friends and any potential threat. The children in turn look up to Tall William for leadership in Ombric's absence. When held captive by Pitch, Tall William refused to show fear in Pitch's presence, and kept the other children calm so the Fearlings would not feed on their fear.
Tall William, as his names suggests is the tallest of the William brothers and towers over the other children, suggesting he may also be the oldest child in the village.
- "I thought that would help."
- "I do too! If I had North's new sword, why, I'd-"
- "You said you had no plans to hurt us."
- "I don't think so, but it's hard to hear anything with all that banging going on."
- "Let's find out."
- "They're making armor."
- "Now they'll be able to go out in the sunlight!"
- "The Fearlings will be too strong for them now with that armor and those weapons."
- "Katherine and Nightlight are in there!"
- "It was Katherine - She was the bravest, and she saved us."
- "If North or Ombric needs a chair, one will come running into place."
- "The Yetis are great cooks."
- "Ombric received a message just before we left. Sandman found her."
- "They are bringing her to the pole."
- Given his height and his leadership over the other children, Tall William may be reaching adulthood, if not already.