Excavator

An Excavator is a class of walker constructs established by the Covenant and later used by its remnants. As their name implies, vehicles of this class were used as excavators and mining platforms. Excavators were also used by the Covenant as heavy weapon platforms, mobile bases, and combat engineering vehicles.

The Excavator class encompasses several lines of vehicles, including the Harvesters, Locusts, the comparatively ubiquitous family of Scarabs, and an unidentified model. Excavators often make extensive use of Lekgolo, with the worm colonies bound together with the vehicle's control systems. The Lekgolo were rarely given complete control of an Excavator, and a supervising Covenant officer and military personnel usually accompany the vehicle. The Lekgolo meta-colonies that operate Harvests from within are known as the Sbaolekgolo.

Tiers
All Excavators were organized by the Covenant into several tiers, each one indicating a walker's size, excavating efficacy, and delicacy. Nine tiers of Excavators are noted in records that survived the Covenant Empire's collapse in 2552, though humanity has only encountered three as of 2558.
 * Tier-one: Type-30 Locusts are designated as tier-one Excavators, designed primarily as offensive tools with no apparent Lekgolo operators.
 * Tier-four: All members of the Scarab "family"—including the Type-29, Type-36, and Type-47 Scarabs and its variants—are classified as tier-four Excavators, often deployed as mining platforms or assault vehicles.
 * Tier-five: Type-58 Harvesters are tier-five Excavators utilized during large-scale excavations.
 * Unknown Tier: Krakens are likely tier-6 or higher due to their massive scale, but it hasn't been confirmed which tier they are.

List of appearances

 * Halo: First Strike
 * Halo 2
 * Halo: Ghosts of Onyx
 * Halo Graphic Novel
 * Second Sunrise over New Mombasa
 * Halo: Uprising
 * Halo 3
 * Halo Wars
 * Halo 3: ODST
 * Halo Legends
 * Origins


 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Palace Hotel
 * Halo: Reach
 * Halo 4
 * Spartan Ops
 * Halo: Spartan Assault
 * Halo: Escalation
 * Halo 2 Anniversary
 * Halo: New Blood
 * Halo: Spartan Strike
 * Halo: Hunters in the Dark
 * Halo 5: Guardians