Originally a marginally improved version of TestBot (a proof of concept AI that performed no actions) JuBot was the first real AI created for 0 A.D. It is no longer actively developed and is kept on for use as the easy AI.
RootBot was a bot created by a group of students for a class project. It is no longer developed, and the last "official" version doesn't work on the latest version of 0 AD. Gudo on the forums has since done one bugfix release here.