A Hydrobot is a Non-Humanoid Hunter Killer unit produced by Skynet sometime before 2018. It features a serpent-like structure with a claw at their head. It is used to patrol the waters. The Hydrobot is based on the present day model of Skynet Research's Aquatic WorkBot, which was used to maintain kelp and seaweed, find minerals and oil, and seek out organic matter. 
As the name implies, a Hydrobot has difficulty operating on land, but they could jump incredible distances and use their metal teeth to cut through even metal.
Terminator Salvation film
Behind the Scenes
- There are HKs similar to Hydrobots in concept arts for Terminator 2: Judgment Day.
- John Connor (Final Battle Version) (1/6th scale collectible figure, 2009)
- Product code: MMS111
- Accessories: Hydrabot, a battle-damaged endoskeleton featured base
- Concept art
- Terminator Salvation film