Nothing is known about Castle's life prior to or as the outbreak began.
At some point during the outbreak, Castle joined a community in Ohio.
Castle and Alves pull Rosita and Daryl away from their assignment to investigate a herd of walkers on the north perimeter. Castle and Alves take Daryl and Rosita to the northern perimeter. Sebastian joins them and orders Daryl and Rosita to retrieve a stash of cash hidden in a house on the other side of the herd. Daryl's group meets up with Castle and Alves and learns that Sebastian has already sent 30 or 40 people to look for the cash. Mercer shoots Castle and Alves dead.
- Killed By
Due to having sacrified 30-40 Commonwealth civilians in order to get money for Sebastian, he was shot in the head by Michael.
This list shows the victims Castle has killed:
- April Martens (Caused)
- Himself (Caused)
- 30 to 40 unnamed Commonwealth residents (Caused)
- Numerous counts of zombies
- "The Rotten Core" (No Lines)
- For reasons unknown, Castle and Alves were excluded from the "In Memoriam" segment on Talking Dead for "The Rotten Core".