The most annoying thing you can ever call one of your video game characters, often used in World of Warcraft by tools.

Newcastle upon Tyne, UK

A toon is a synonym for a character in a video game that is a role-playing game, usually used only in the context of Massively Multiplayer Online Role-playing Games (MMORPG), such as World of Warcraft.

Character, avatar, or toon are synonyms in this context.
(Avatar is a misnomer, however.)

In role-playing games, a great deal of effort is spent in creating a unique persona or character before play begins. During character generation, the player makes choices that will affect the gameplay, such as appearance, name, gender, race, and class. Once created, these characteristics are immutable, as they define the play experience. The selection of class determines the strategies the character will use to succeed.

In short, Role-playing games have great replay value because a player can re-experience the game using a new character or toon.

ETYMOLOGY

Toon is presumably a contracted form of cartoon; video game characters are animated, after all. The origin of this term can be attributed to the standard root of all leetspeak (internet jargon): a need for efficiency for lazy typists.

Toon is probably used because it is shorter and easier to type than the word character. Anyone familiar with these games can easily surmise the meaning of the term from context. Furthermore, the term avatar is avoided as it can possibly create confusion. In roleplaying games, avatar also refers to the incarnation of a deity.

A paracytic creature that swims up someone's anus and attaches itself to the victims sphincter. Once it imbeds its fat unpleasant head into host, it is almost impossible to remove and causes serve pain and discomfort. Residing mainly in Port Phillip Bay Victoria, but will travel as far as Northern NSW and South Australia if conditions are suitable.

Another word for tool, clown, dip-shit, dufuss, dumb-ass, etc. etc.

Toon short for Cartoon.

Synthetic Marijuana, K2,

A really... really... really Canadian way to refer to a character in an MMORPG. Similar to how sliced round ham is called Canadian Bacon... They call a character a "toon"