The first model of Sentinel robots to appear in the Marvel Comics universe. Created by anti-mutant bigot Bolivar Trask, the Mark One Sentinels were programmed to protect humanity from the threat of mutant criminals and extremists. However, Trask was not in total control of his creations as the artificial intelligence Master Mold had deemed it necessary to dominate human society in order to purge the mutant population. As the Master Mold constructed hundreds of Sentinels to conquer the world, Trask eventually came to realise that not all mutants were a threat and that he had created the greatest threat the world had ever seen. With the aid of the mutant superhero group the X-Men, Trask sacrificed himself by destroying Master Mold and the Sentinel factory. The majority of the Mark Ones were destroyed during this incident.
- Appearance - Sentinels are 20ft tall humanoid robots with purple bodies and vaguely humanoid faces.
- Programming - Mark Ones are programmed to hunt down and either capture or kill mutant targets. Their primary purpose is protecting humanity from mutants, but their AI allows them to determine the best way to achieve this function, thus resulting in their attempts to dominate mankind in order to expunge the mutant population.
- Strength - Sentinels are highly resilient to damage, their bodies being heavily armoured. They are capable of lifting up to 20 tons.
- Flight - Jets built into the Mark One's feet allow them to fly under their own power.
- Weapons - Mark Ones are armed with various energy beam weapons which can be fired from their chests. These energy blasters have electric, stun and heat settings. They also have a disentegrator beam that vaporizes inorganic matter.
- Scanners - All Sentinel models are capable of detecting the active X-Gene, allowing them to identify mutants from normal humans.