Builder Bob was in charge of the memorial to the fallen combatants of the Battle of Lumbridge during the Lumbridge Rebuildathon. He was found in Lumbridge, between the resource stockpiles and Foreman George. He now has been removed from the game, and players can no longer contribute to the memorial.
The memorial, which depended on player contribution by the end of 2 November, was designed to coincide with RuneFest 2013 and required RuneFest attendees to work with players at home to complete it. He accepted resources in the form of stones to construct the memorial. Player contribution to the memorial had a hidden limit of 1,500, similar to the daily limit of the Lumbridge Rebuildathon.
- His name is a reference to the children's television show "Bob the Builder".