In the Mass Effect universe, Harvesters are giant, serpentile creatures that can be found on several planets. During the Reaper War of Mass Effect 3, the Reapers have obtained several Harvester specimens and transformed them into hellish cyborg monstrosities.
The augmented Harvester acts as a sub-orbital transport vessel and can carry other Reaper ground troops into battle. It flies on large draconic wings and can decimate enemy forces with repeated blasts from the twin artillery guns mounted on its head. Harvesters carry no shielding and can be brought down with concentrated incendiary fire, but in many cases a Harvester will drop off Husks and leave the battlefield before it takes too much damage.