Teleporter

Teleporters allow for instantaneous transport over short distances to another teleporter or teleporter exit point. Although they act similarly to Forerunner Teleportation Grids, they are unable to transport over long distances.

Multiplayer
In Multiplayer, these are seen on levels such as Blood Gulch and Beaver Creek. In multiplayer maps, however, teleporters can be found on Earth. It is unknown about the canonicity of teleporters on certain maps.

In Halo 3, teleporters were present in hardly any multiplayer map because Bungie thought it was too easy to "camp" near them and get easy kills. Despite this, teleporters were reintroduced in the recently released map Avalanche, as well as appearing on Cold Storage. Teleporters are available, however, in Forge for every Halo 3 map. In Halo 3, when a person enters a teleporter and is going at a higher speed (most likely caused by a jump from above), they keep their momentum and come out at the same speed, but in the direction it is aiming.

List of Maps with Teleporters
Halo: CE:
 * Battle Creek
 * Blood Gulch
 * Boarding Action
 * Chill Out
 * Chiron TL-34
 * Damnation
 * Danger Canyon
 * Death Island
 * Derelict
 * Gephyrophobia
 * Ice Fields
 * Infinity
 * Rat Race
 * Sidewinder
 * Wizard

Halo 2:
 * Ascension
 * Beaver Creek
 * Coagulation
 * Containment
 * Gemini
 * Headlong
 * Relic
 * Warlock
 * Waterworks

Halo 3: ''Note: Every map in Halo 3 can have teleporters placed in Forge. The maps listed are ones that have teleporters by default.''
 * Avalanche
 * Cold Storage
 * Sandbox (not visible from the ground or removable in Forge).

Halo Wars:
 * Blood Gulch
 * Fort Deen
 * Labyrinth

Trivia

 * Teleporters were present in Halo Wars' campaign and multiplayer.
 * In Halo 3, except for the couple of maps with teleporters listed above, the teleporters on other maps only appear in Forge. Bungie, however, provided the gamers with the Man Cannon, a different way of quickly going through the map.
 * A clever, though usually considered cheap, strategy involving teleporters is to go through one, then immediately move backwards. If the space behind it goes back far enough, then you can camp behind the teleporter.
 * On Cold Storage and Gemini, the teleporters are blue instead of the normal green.
 * In Halo CE and Halo 3, it is possible to block the teleporters (especially in Blood Gulch) with a vehicle or by simply standing on them.
 * Telefragging is the use of a teleporter to kill somebody standing on top or inside another teleporter. The player standing on top of the "receiver node" of the teleporter will have the screen slowly turn white before being killed as a "suicide"(this only occurs in Halo: Combat Evolved, Halo 2, and Halo Trial, in Halo 3 it says it is blocked).