BOB

The B.O.B. is a special type of enemy encountered in Halo: Reach. The B.O.B.s usually take the form of gold-armored Sangheili Rangers. In the ONI: Sword Base level, B.O.B.s take the form of a white-armored Elite with randomly generated armor, ranging from Minor to Field Marshall. It is also possible for B.O.B.s to use Armor Lock.

Description
You receive a medal for killing a B.O.B. named "Seek and Destroy". However, the medal used to only be viewed from Bungie.net. In the post-game carnage report, the B.O.B. is referred to as an "Elite Light Vehicle". On Bungie.net, under the "Enemies" tab they are titled "Elite Ranger," subtitled "BOB," and their description is simply "Wipe them out..." There are three daily challenges related to B.O.B.s: "Golden Opportunity," in which the mission is to "Find and kill the Gold Ranger-class Elite in any Campaign mission on Heroic or harder."; "If it bleeds ...," in which the mission is to "Find and kill the Gold Ranger-class[sic] Elite in any Campaign mission on Normal or harder."; and "Golden Tree City," in which the mission is to "Find and kill the Gold Ranger-class Elite in a Banshee, fast and low, while on New Alexandria, on Legendary." The first two challenges appear roughly every month or two, but Golden Tree City has appeared only eight times (1/19/11, 11/13/11, 2/29/12, 5/20/12, 6/19/12, 9/19/12, 7/22/13,8/6/13).

B.O.B. appears or can be made to appear exactly once on every mission, with the exception of The Package. On Exodus and New Alexandria, the appearance is as a Banshee B.O.B. On ONI, B.O.B. is not in golden armor.

The name "B.O.B." is a reference to Bungie's Marathon video game series. In the series, all of the encountered human characters, besides the player, are known as "B.O.Bs". "B.O.B." is an acronym for "Born on Board", a reference to the characters having been born on board the titular colony ship. The AI Leela instructed the player to save as many as possible, but Bungie encourages the player on secret terminals to kill them all. The Vidmaster's Challenge states that the player must "Never, ever leave a single B.O.B. alive."

BOBs are considered easter eggs, and thus have no canonical explanation in the Halo story.

B.O.B. locations
Basic multiplayer map knowledge is helpful to finding some B.O.B.s. Spawn locations are accurately determined using theater mode. Some B.O.B.s wander or disappear, so players may encounter them far from their spawn points or not at all. While weapons vary depending on the difficulty, spawn locations do not.

Winter Contingency
There are seven spawn locations on Winter Contingency, but several are close to each other, so during game play, it appears that there are only three. All appear near the three civilian settlements in the second portion of the mission. B.O.B. wields Plasma Repeaters from Easy-Heroic difficulties, and Concussion Rifles on Legendary. On most missions, if the mission is restarted, B.O.B. will spawn in the same location. This is not the case on Winter Contingency. When using the glitch that causes the player to fly the Falcon that Jun normally rides in it is possible for the level's three B.O.B.s to hijack the Falcon and use its chaingun on the player if the player gets too close to one. Often a checkpoint will occur as it hijacks the Falcon causing the mission to become almost impossible to complete as it will shoot you down constantly.
 * There are three spawn locations at the first encountered settlement. Depending on the actions of the player, B.O.B. will soon set off along the road to the riverside settlement, or towards the cliffside settlement.
 * There are two spawn locations at the cliffside settlement. B.O.B., will plot a course for the riverside settlement soon after he spawns.
 * There are two spawn locations at the riverside settlement. B.O.B. will dash across the bridge and head up the road to the cliffside settlement.
 * On Legendary, at the very beginning of Winter Contingency, an Elite Covenant in active camouflage will dash to the right and disappear about where the Moa appear. He is often referred to as Bill, so as to distinguish him from B.O.B., with whom he is often confused. If killed, he will drop a data pad (pick it up and read it). He is neither a Ranger nor golden (he's a coppery color, as can be seen in theater mode), and his death does not earn one an "Elite Light Vehicle" kill in the carnage report, nor a Seek and Destroy medal.

ONI: Sword Base
In this level, a B.O.B. will spawn in one of two locations. Each B.O.B. encountered on this level will be a randomly-generated Elite wearing white armor and dual-wielding plasma rifles. In this mission, B.O.B. does not seem to disappear until well after being spotted.

Map data (not available to the player) indicates that there probably were plans for three more spawn locations—one at Faragut Station, one at Airview Station, and one in the area in between—but these spawn locations seem to have not made it into the final game play. (See the "Bob" forum on bungie.net, p. 199.)
 * The first spawn location is in the Courtyard area after the player returns from the missions at Faragut and Airview stations. The spawn location is to the left of the garage entrance. Once detected, this B.O.B. will retreat to the area where the mission began, giving the player the impression that there is something important back there.
 * The second spawn location is in the room below the damaged area with the General Elite. He will be under attack by some Marines across the bridge. If you sneak up on him, do not assassinate him as the amount of time you have to kill him will likely run out, and he will disappear in the process. Also, you must attack him first before he attacks you, so make the initial strike count.

Nightfall
Three spawn locations:
 * The first spawn location is near the broken bridge behind the far building at the start of the level. You can find him here.
 * The second spawn location is in the section where you assist the local militia, reminiscent of the Firefight map Waterfront. He spawns on top of the building on the left.
 * The third location is at the Powerhouse (reminiscent of Multiplayer map Powerhouse) where Jun plants the bomb. He spawns near the back on the bridge above where the Rocket Launcher is found.

Tip of the Spear
This is the only level on which B.O.B. cannot always be made to spawn. There are four spawn locations. If B.O.B. spawns at the first AA gun and the mission is restarted, then he will spawn there again. If he spawns under the dome and the mission is restarted, then he will spawn under the dome again, but not necessarily in the same location. If he does not spawn in any of these locations and the mission is restarted, he will again not spawn.
 * As you head for the first AA gun, there will be a hill to the left. The first spawn location is on this cliff face.
 * The other three spawn locations are under the dome after the Falcon crashes. The locations are in between the rocks among the Skirmishers and Grunts; and two locations over on the far left near the first bravo objective in Invasion on Spire. This B.O.B. always wields a Fuel Rod Gun, so he is very dangerous, especially on higher difficulties.

Map data (see the BOB forum on bungie.net, pages 199—203) and discussions with bungie employees (http://forums.bungie.org/halo/archive37.pl?read=1116858) indicates that there was supposed to be another spawn location at the second AA gun. This spawn location is apparently underground, which may explain why it hasn't been observed in game play (including theater mode), and why B.O.B. doesn't appear in some missions.

Long Night of Solace
The first spawn location in this mission requires particular actions on the part of the player, so it is possible to go through the mission without seeing B.O.B., even in theater mode.
 * At the beginning of the level after securing the beach, when Army Troopers are fighting the covenant forces being dropped from Spirit dropships, wait for five or six dropships to arrive (counting both beaches). With the fifth or sixth Spirit (almost four minutes after first securing the beach), it is possible for a B.O.B. to be deployed via a Drop Pod. The Drop Pod will land in one of three locations: On the beach near where the Wraith is deployed (to the left of the entrance to the facility); or in one of two proximate locations along the path to the facility. If B.O.B. does not show up in a Drop Pod, he will spawn in one of the later locations. This B.O.B. disappears very quickly (maybe half a second), but if you get a shot into him, he will stick around and play. If you miss him and do not enter the building (or even if you get him but want to relive the glory), then reverting to last save will return you to the point when the beach was first secured. B.O.B. will again arrive by Drop Pod, but not necessarily in the same location. This is the only B.O.B. that leaves behind evidence that he was there (the Drop Pod).
 * The second spawn location is in the control room (the bridge) near the back of the room. (Maybe he's steering the ship?) If you are quiet enough, you can assassinate him for an easy 'Seek and Destroy' medal. Due to the fairly dark lighting this B.O.B. can be easy to miss, or easy to kill without knowing it.
 * The third spawn location is when you have to defend the Pelican after returning from the bridge. It is on one of the platforms at the back and left as soon as you enter the room. Try to snipe him, although this method almost always results in failure due to the fact he runs behind a shield, making it very difficult to shoot him.
 * A fourth spawn location is on a landing pad (outside the building) where enemy drop ships are fired at by an Army Trooper with a rocket launcher. If you wait at the landing pad a B.O.B. with eventually arrive. (This was discovered on normal difficulty.)

Exodus
There are no Sangheili on Exodus, so there cannot be any Golden Ranger Sangheili ... or are there? On this mission, there are "Banshee B.O.B.s" that exhibit behaviors similar to that of the Golden Ranger Sangheili. These Banshee B.O.B.s are pilotless—no feet can be seen sticking out the back (even in theater mode) and no body is seen when they are destroyed. They cannot be hijacked, and destroying them does not earn the player a "Seek and Destroy" medal, nor an "Elite Light Vehicle" kill. However, destroying a Banshee B.O.B. will win the "Golden Opportunity" and "If it bleeds ..." challenge when these challenges are active!

Banshee B.O.B.s will not shoot at you and boosts constantly, though their exhaust is not quite the same as the normal boosting exhaust.

The appearance of Banshee B.O.B. on Exodus requires an action by the player. Two of these triggers are unavoidable, but the last isn't, so it is possible to play the mission without the appearance of a Banshee B.O.B.
 * The first spawn location is in the area between check point alpha (where one gets the jetpacks) and the landing pad. It is in the open area that the snipers (with beam rifles) shoot across. The trigger seems to be crossing the lower bridge and coincides with a checkpoint. B.O.B. appears far right and flies through, then shrinks and often crashes into a building.
 * The second spawn point occurs shortly after boarding the Falcon on the helipad. He will appear lower left soon after the "I should have been a watchmaker" title fades out. This is the same location that the Banshees come from when you first receive the jetpack. You can increase your chance of wiping out this B.O.B. by boarding the right (passenger, or starboard) side of the Falcon which lands on the right side of the helipad. This requires killing the Marine which usually occupies this seat if playing solo.
 * The third spawn location is during the missile battery activation sequence in the Beachhead area at the end of the level. The trigger for this B.O.B. to appear seems to relate to crossing some point just past the first missile battery (stepping onto the bridge). It spawns somewhat above where the Falcon drops the player off for this area, criss-crosses the area very quickly, and will disappear as it heads in the direction of the previous area's beach. As with other Banshee B.O.B.s, it moves quite quickly and does not fire at the player.

New Alexandria
This Banshee B.O.B. has spawned as late as 20 minutes into the mission, so it is not clear what the trigger is, though it is likely related to fending off waves of Banshees.
 * There is one spawn location on this mission, at a very low altitude in the open area WNW of Club Errera. It flies around an altitude of 100-150m and can be made to regularly spawn by locating the spawn point and squatting there, fending off waves of Banshee pairs until he appears, somewhere around the five or six minute mark. It is incapable of fighting against the player and can only boost. It will fly rapidly to Club Errera and will stay in the area for a few minutes, before flying outside the map's boundary. A checkpoint will occur as it does this.

Like the Banshee B.O.B.s on Exodus, destroying this Banshee B.O.B. will trigger the "Golden Opportunity" and "If it Bleeds ..." daily challenges, as well as the "Golden Tree City" challenge. Other than this and their behavior, there are no other indications that these are B.O.B.s (no Golden Elite Pilot inside, no medals, no Elite Light Vehicle kills in the carnage report).

The Package
There are three spawn locations.
 * The first is in the courtyard, to the left on the side of the bridge where the Bridge spawn is in firefight, in amongst the three Jackals. This B.O.B. will only attack with melee and grenades. It is best to kill the Jackals with a grenade before engaging the B.O.B., and, if skilled, the player can lure it down for Noble Team to take care of. Or circle to the right and snipe him while the rest of Noble keeps the other enemies occupied.
 * The second spawn location is at the button that the player pushes to go down under the glacier. Once the player enters this section of Sword Base, B.O.B. will stay around for another 40 seconds. He is therefore often missed during game play, as the player must first get past the cloaked elites and the general. Be careful with him, as he is very clever.

When a Banshee is hijacked or destroyed, a replacement comes down from the ceiling a little later. After Halsey announces "Just a little bit longer," the Banshees under the glacier turn and boost towards the ceiling. If these two incidents coincide, it is possible for a Banshee to come from the ceiling and constantly boost horizontally, giving it the appearance of a Banshee B.O.B. However, it is not a Banshee B.O.B.
 * The third spawn location is under the glacier. He spawns inside the Phantom that drops of the second Wraith at the end of the ice shelf. The Phantom is otherwise empty.

The Pillar of Autumn

 * When finishing the canyon area of the map (the area with numerous Drones), grab the Laser, and look to the opened area in the mid-point of the area which is designated as Boneyard in Matchmaking. This one is clever, so only engage if you are very skilled in lasering enemies.
 * After the mentioned area, go up the stairs and pick up the Sniper Rifle and look to the garage(where the Scorpion and Warthog spawn in the Invasion mode of said Multiplayer map). A B.O.B. will be there if the previously mentioned one does not. This is one of the easiest B.O.B. kills, since there is little cover for the B.O.B., and a sniper rifle is available for the player to use.

Lone Wolf

 * After fighting your enemies from anywhere from 3 1/2 to 11 minutes, a B.O.B. will appear wielding an Energy Sword. He is the same color as the General class elites attacking you, so he may go unnoticed. Also, since the B.O.B. spawns out near the Wraiths, it is possible for him to be splattered by one of the tanks on his run towards the player, making it seem as if he never spawned. This BOB was likely placed to kill a player who has been playing on the level for too long (as the player is expected to get killed sometime during the level), as B.O.B.s are more powerful than standard Elites, and this B.O.B. is particularly aggressive.

Trivia

 * The BOB's primary weapon often is dual wielded Plasma Rifles. But B.O.B.s have been sighted using other weapons too.
 * Each BOB has a set time limit before it vanishes. For some B.O.B.s, this time frame begins as soon as it is alerted to the player's presence. For others, the countdown begins once the player enters a certain area, thus it is possible for the player to miss the BOB entirely if it is not spotted. Also, if you assassinate a BOB, it might disappear. If it does, you'll be assassinating air.
 * In Halo: Reach, all ranks of Sangheili, even Sangheili Ultras, even though they're already white, can be B.O.B.'s.
 * In the level ONI: Sword Base, B.O.B.s can be any Sangheili armor variant.
 * On 1/19/11, Bungie revealed the location of a Gold Ranger-class Elite in the Challenge titled: "Golden Tree City" the description read: "Find and kill the Gold Ranger-class Elite in a Banshee, fast and low, while on New Alexandria, on Legendary". Whether or not he is a BOB is unknown, as even though all Gold Ranger-class Elites are B.O.B.'s, killing this specific enemy doesn't result in a Seek and Destroy medal, nor the mention of an "Elite Light Vehicle" in the carnage report, even though it fits with the classical description of a B.O.B., as he is in a very fast Banshee which avoids combat, and whose tail is permanently lit even when the vehicle isn't boosting making it look largely different than other Banshees. As he is in a driver-less Banshee, there's no body seen when the Banshee is destroyed, so it is impossible to check if he is indeed a Gold Ranger-Class Elite. This, along with the fact that he gets killed while inside a vehicle, and not directly by the action of the player, could also explain the lack of an actual B.O.B. kill, and its absence from the carnage report as well as the lack of a Seek and Destroy medal.
 * Only one B.O.B. will appear on any mission, though it is possible to kill a B.O.B. and "Revert to last save" before reaching another save point. In this way, multiple "Elite Light Vehicle" kills can be racked up in the same mission
 * The only B.O.B.'s seen to date have been Gold or White in armor color and any Sangheili rank in Halo: Reach (Minor through Field Marshall).
 * Most B.O.B.'s are seen with Dual Plasma Rifles, Fuel Rod Guns, Concussion Rifles, and Energy Swords (Energy Sword Seen on Lone Wolf, only one).
 * In the mission Long Night of Solace, if you wait for the drop pod near the Wraith and time your jump to assassinate him just right, you will get the "If They Came to Hear Me Beg" achievement, which is quite odd because if you miss, you would easily survive the fall.