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A mobile, or "mob", is a non-player character (NPC) or "monster" in a computer game, for example a role-playing video game or MMORPG or Multi-User Dungeon.

Purpose of MOBs in gaming[]

In many games, killing monsters may be required to gather experience points, money, items, or to complete quests.

Sometimes the combat is player initiated. In other cases, the non-player character is aggressive, and may challenge any player's character which comes to its attention.

A player engaged by an NPC is said to be "have aggro". This marks that player as the primary target of the attacking mob(s). Combat between players and mobs is called player versus monster (PvM) or in a broader sense, player versus environment (PvE), as opposed to player versus player (PvP) battles where the emphasis is on defeating an opposing player.

Monster versus monster (MvM) battles also take place in some games.


Perhaps the most commonly-held belief about the origin of the term is that it derives from mobile or mobile object.

One possibility is that the term comes from the variable name given by Dr. Richard Bartle in 1980, when he added "mobiles" to the MUD created by Roy Trubshaw in 1978.

In Dr. Bartle's words:

When I took over programming MUD1, all objects except player characters were static, ie. they didn't move. I wanted some objects that did move, so I could use them for monsters etc.. I needed a name, for programming reasons if nothing else (the variable names, the record structure name). I didn't want to call them "monsters", though, because I could see their being used for non-monsters, eg. helpful humans.

I decided to go with "mobiles" as a familiar form of "mobile objects", and because of the happy coincidence of the name's existing use for those hang-from-the-ceiling decorations that consist of a bunch of seemingly independent entities moving within predefined constraints. Thus, mobiles were born. The name was passed down through generations of subsequent virtual worlds, until in the late 90s people started shortening it to "mobs". Thus, mob doesn't stand for Mobile OBject, it's a shortened form of "mobile", which in turn is the quick name I gave to mobile objects in MUD1. "Man Or Beast" is a retro-fit.[1]

The term mobile was later replaced by NPC or Non-Player Character for some uses: dialog or quest givers, vendors, and trainers to name a few.

Backronyms such as "monster or beast" and "mere ordinary beast" have been developed.


MUDs (multi-user dungeons)[]

The term "mobile" was used by Richard Bartle in a paper describing an early MUD which was being constructed as a research project at the University of Essex. Although it originally referred to an object that could move (as opposed to one that couldn't), one reviewer of the paper misunderstood the term to be a reference to the classic children's toy or sculpture that goes by the same name - and referred to it as "an incredibly beautiful analogy to those hanging toys, which appear to move around randomly as if alive, while in fact being composed of mechanical parts and operating in accordance with fixed scientific laws". (Bartle was also suitably impressed by the analogy, and wished he'd thought of it.[2])

Other MUDs and MUD-like software use a variety of terms to describe these as objects, emitters, and actors.


A "MOB" in an MMORPG usually refers to the generic monstrous NPCs that the player is expected to hunt and kill rather than NPCs that engage in dialog or sell items. Named mobs are distinguished by having a proper name rather than being referred to by a general type ("a goblin", "a citizen", etc.).


  1. Email conversation between Richard Bartle and Erik Anderson April 14th 2008
  2. "Designing Virtual Worlds" (2003), Richard Bartle, ISBN-10: 0131018167, ISBN-13: 978-0131018167

This page uses content from Wikipedia. The original article was at Mob (computer gaming).
The list of authors can be seen in the page history. As with MUD Wiki, the text of Wikipedia is available under the Creative Commons Attribution-Share Alike License 3.0 (Unported) (CC-BY-SA).