The World 61 Glitch

The World 61 Glitch is one of the most famous glitches ever. When Jagex released the God Wars Dungeon teleportation tablet on 12/23/08, something went wrong. Badly wrong.

The Glitch
A player named "Atticus911" had been created just that time, and he was using a program called Runescape Cheat Codes to do stuff. He looked at a code called "911" and thought that sounded good, so he used it. Then, Jagex got multiple calls about a fire, and while they were distracted, he bypassed the update, and, and made it accessible to free players.

Players all over the game world found God Wars Dungeon teleportation tablets (GWDTT) in World 61, but they couldn't use it. Then, World 61 could not handle the traffic because they never had the status "FULL" before, and the F2P players teleported to God Wars Dungeon, and were killed. However, Atticus911 used Code 341, which changed players' respawn point to the God Wars Dungeon, and Code 345, which prevented players from logging out. This trapped all of the players in the server to the dungeon.

Jagex's Notice
But Mod Craddock got less calls, and he saw what had happened to the server. He tried to do something, but Atticus used code 987 to make the game freeze for all players. By now, the fire companies had stopped calling, and JMods looked to see what had happened.

Aftermath
Jagex saw that Atticus was the only one not in the God Wars Dungeon. He said stuff like "Haha, I'm killing bad" and "Cheatin is good" and was banned on the spot. To stop the pandemonium in the God Wars Dungeon, they deleted all monsters in the dungeon for a moment, and the Mods rescued the items before they disappeared. They decided not to release the GWDTT, and it became a discontinued item.

Trivia

 * 911 is the number for a emergency.