From Joomla! Documentation

A registered bot account. Edits by an account with this set will not appear by default in Recent changes; this is intended for mass imports of data without flooding human edits from view. (To show bot edits, either click the "Show bots" link on the Special:Recentchanges page, or append &hidebots=0 directly to the page URL, or like this on Joomla! Documentation.)

Bots used by server admins

Delete page script
bulk deletion of pages
Maintenance script
as the name implies, performs maintenance tasks
Migration script
content migration from (old) wiki

Bots used by users

Pending accounts: