| Animal Hunter Killer|
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.
Hydrobot are quite often in the Salvation against Resistance fighters. Where the resistance have capture one of it to amplifier to go offline for testing. Later in the movie, where they ambushing the pilots and causing the entire chopper to crash into the river. Later, they begin to swarm the wreckage of the helicopter. While John is the only one who left to fend off against these killer until Marcus come out of the water to dispatch the machine. Before making a deal with John to save Kyle in the Skynet Stronghold.
- It does not seem "smart", when John Connor ordered the test of "shut down" code, referring as "We'll test it on something small and easy to catch".
- It's not clear how Hydrobots propel themselves through the water. Based on the design, it's logical that they have some sort of propeller in the inner part of their chassis.
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