jul 1, 2015 - Ban potion exploit
Description:
This exploit involved a potion with certain effects, any player that got hit with it when god mode is disabled, the player would not join the server until restart, in some servers, it would never restart, so it would be a perma ban in some cases. (This exploit was eventually patched by Mojang in 1.9)
Added to timeline:

My timeline test
Test timeline (nothing important)
Date: