Some people on the wiki run bots to automate tedious tasks. Most of the time you won't even see them working, because a bot's edit activities are hidden by default. You can chose to see recent edits by bots by clicking Show bots on the Recent changes page.
Occasionally a bot may do something you don't like. Feel free to revert the edit and comment on it on edited page talk page and/or the bot owner's talk page, just as you would if a human made the edit. The bot owners are indicated on the bots' user pages. Very occasionally a bot may go wild and start behaving destructively. Each bot lists a way to shut down the bot before it can use our nuclear arsenal to annihilate all mankind. Please don't shut down a bot just because it did one thing you disagree with.
ReletBot
ReletBot creates new graticule pages based on the names users provide in All Graticules, updates neighbouring links if graticule names are changed, and propagates other enhancements to graticule pages. If you want your graticule page to stay exactly the way you made it, add the Template:Maintained to the page, and ReletBot will leave it alone. It becomes your responsibility to ensure outgoing neighbour links are current and to update to the latest map template.
Owner Relet monitors irc://foonetic.net/#geohashing while the bot is running, and you can contact him there with problems.
AperfectBot
AperfectBot looks for future expeditions that are being planned and reports them on Current events. It also produces a list of expeditions for users and graticules who have properly configured it.
AperfectBot (a.k.a. Ape) has a Distraction Banana section on its page. Any text there will halt the bot. As was stated previously, please only use this if the bot is misbehaving very badly. For isolated or minor problems, use the bot's talk page to voice your concerns.
JesseWBot
User:JesseWBot does various random maintenance tasks when I get around to running it. It should not do anything fully automatically.
FippeBot
FippeBot tags expedition pages with {{location}}. Contact Fippe if there are problems or suggestions. In case of emergency, change the text here to stop the bot from running.
SkyNet
Joannac maintains a secret fleet of killer bots that protect us from spam and could never go wrong, so all the power of the wiki is in their hands, with no known way to shut them off.
DarkBOT
User:DarkBOT was written by User:Darkid as an effort to notify users about geohashing locations that are within some (sane) distance. It's hosted on Github, and thus hopefully won't have any availability problems.