Honor Guard Councilor

"Honor Guard Councilor" is a fan-derived term describing a strange Elite that serves as the final opponent in the Halo 2 Campaign level Gravemind. He appears to be wearing the gauntlets and greaves of an Honor Guard Ultra, with the helmet of either a Councilor, an Ultra Elite, or an Honor Guard Elite. The Elite's appearance can be attributed to a glitch in the game's programming due to a programmer typing incorrect coding; it was meant to be a Zealot.

Appearance
The Honor Guard Councilor, who appears at the fore of the bridge between the Mausoleum of the Arbiter and the Far Tower, is flanked by two SpecOps Elites wielding Plasma Rifles or Carbines. The Councilor is armed with an Energy Sword, and can be dangerous if a player does not know how to dodge his attacks. The three Elites appear after the Master Chief has killed the Ultra Elites, Hunters, and Brutes fighting in the Mausoleum of the Arbiter, and has moved to intercept the High Prophet of Truth.

Variations
Though the armor is always white with Honor Guard pieces, there are some variations, mostly with the helmet. In addition to the helmet variations below, there are occasions where the glitched Elite has Rtas 'Vadum's face -- that is, where the Elite is missing two mandibles.
 * Councilor helmet, standard blue lights on body armor
 * Councilor helmet, Rtas 'Vadum's face, red lights on body armor
 * Red Honor Guard helmet
 * Ultra Elite helmet
 * Mysterious helmet
 * A helmet that resembles the Councilor helmet in form, but has a different texture and some small differences in shape.
 * No helmet
 * Some Elite corpses in the level lack a helmet, which is why this is possible.

Combat
The Honor Guard Councilor is extraordinarily powerful and on Normal difficulty or higher requires at least two Fuel Rod Gun hits to kill, or multiple Energy Sword slashes to defeat. The Honor Guard Councilor is programmed to have the power and skills of a Zealot. It always wields an Energy Sword.

Explanation
The Honor Guard Councilor's appearance results from the usage of a missing tag.

In Halo 2, every enemy in the Campaign has variations, which increase the game's realism. The variations would be chosen at random each time a level was played; they determined that enemies would act and sound differently. This differs from Halo: Combat Evolved, where some enemies, like Elites, always used the same lines.

Each Elite tag was suffixed with an underscore and a three-letter code denoting the Elite's voice actor. Tags whose name ended in  ("dogmatic"), for example, were voiced by Norm Woodel; tags ending in   ("Scully") were voiced by David Scully. So in most maps, there are two tags for each Elite rank, with the tags having differing voice actors. This can be seen in many levels, including The Great Journey; when you exit your Spectre/Wraith, there is an Elite saying either:
 * "The Arbiter? I thought he was dead. Hold your fire! The Hunters have come to our aid, Arbiter. They will stand by our side." in a calm and steady voice, or:
 * "The Arbiter? I thought he was dead. Hold your fire! The Hunters have come to our aid, Arbiter. They will fight by our side." in a fast and energetic voice.

So these are all of the Elite tags in The Great Journey.
 * Minor_dog
 * Minor_scl
 * Major_dog
 * Major_scl
 * Stealth_dog
 * Stealth_scl
 * Stealth_Major_dog
 * Stealth_Major_scl
 * Ultra_dog
 * Ultra_scl
 * (and so on.)

On most levels, all a programmer has to do is code the game to produce one Minor Elite, for example, and the game itself will randomly choose between the Minor_dog and Minor_scl variations. Programmers do have the option to force the game to use a particular variation.

However, not all levels have both sets of tags for all enemies. In Metropolis, for example, all Grunts sound the same, because the tags voiced by Brian Posehn were omitted from the map's code, leaving only the Grunts that were voiced by Joseph Staten. Bungie decided to use only one of the two Grunt variations in the game.

This was also done on Gravemind: Elites'  tags were omitted from the level, such that only   Elites could be used. Because of this, the programmers would have to manually add  onto all of the Elite tags. Unfortunately, the game's programmers accidentally coded the game to spawn a "zealot_dog" -- they had used the wrong variation suffix. Since this variation was not in the map, the game could not find it.

At this point, the game knows to spawn an Elite with the power and weapons of a Zealot, but it does not know what the armor is supposed to look like. It automatically chooses the default armor color, white, but there is no default helmet. The game thus chooses between the available helmets (or lack thereof). The face is also randomized, sometimes causing the glitched Elite to have Half-Jaw's face and eyes. And for unknown reasons, the game always enables the "Honor Guard" armor -- all Elite tags have a setting that gives them Honor Guard armor, but it is supposed to be disabled on most Elites, including Zealots.

Trivia

 * Sometimes, but very rarely, this Elite appears as a normal Honor Guard Ultra, or even more rarely, a simple Ultra Elite.
 * In Halo 2 Vista, the error is partially corrected -- the Elite's shields are normal.