Promethean Watcher

The Promethean Watcher is a Forerunner Sentinel variant. Watchers are part of the mechanical Promethean forces created by the Ur-Didact near the end of the Forerunner-Flood war as a desperate attempt to combat the Flood. Numerous Watchers were encountered on the shield world Requiem in summer 2557.

Overview
In the battlefield, Watchers act in a supporting role, assisting Promethean ground units with aerial combat screening and often forcing opponents to engage the Sentinel first. Each Promethean Knight unit carries a single Watcher or more in the back of their armored carapace, from which the Watcher can be deployed at will. The Watcher is an integral part of the Knight, as it shares the same digitized essence, part of which is split off when the Watcher separates from the Knight's carapace.

The Watcher is capable of healing and augmenting damaged allies, providing them with hard light shields, and can catch and return enemy ordnance, such as grenades, with a gravity-displacement field. They are armed with a built-in Boltshot. Watchers can resurrect destroyed Knights from the small orb of light they leave behind upon death; however, this can only be performed once for each individual Knight. They are also capable of summoning Promethean Crawlers to the battlefield by conjuring the Crawlers' forms from raw material in the ground. Watchers are also capable of building beam turrets.

Appearance
Unlike the angular appearance of most Sentinels, Watchers have curving carapaces, a defining characteristic of Promethean war machines. They have a number of appendages, including what appear to be legs hanging below the midsection and two large disks on both sides. Most of these segments lack physical joints and are held together by energy fields. Above the midsection there appears to be a head with stylized facial features. Like the other Promethean constructs, Watchers under the Ur-Didact's control possess orange lighting, in contrast to the blue-lit appearance typical of Forerunner constructs.

Trivia

 * The Watcher, along with the Promethean Crawler, was first seen in a leaked image from McFarlane Toys. However, it was first mentioned as the "Watcher Sentinel" several months earlier in Halo: The Essential Visual Guide.
 * An outline of the Reclaimer symbol, in reality the Marathon logo, appears on the Watcher's midsection despite Bungie owning the rights to the Marathon franchise.
 * Shooting the tiny face on the Watcher counts as a headshot and destroys the whole body. However, the face is so small and the Watcher is protected by weak shields, that aiming for it is not very practical.
 * Promethean Knights are capable of deploying multiple Watchers from their body, not just one.

List of appearances

 * Halo 4
 * Halo: Silentium