Although Bolivar Trask was an anti-mutant bigot, he learned the error of his unfair judgment of mutants and sacrificed himself to stop his Sentinels from conquering the world. His son Larry also hated mutants (despite being a mutant himself) and harboured a grudge against the X-Men for the role they played in his father's death. Continuing his father's work, Larry developed a new line of Sentinels more advanced than his father's, and he sent them to attack the X-Men. He wore a special medallion that prevented the Sentinels from identifying his mutation, but during their battle this medallion was damaged and his Sentinels turned on him. During their battle with the X-Men, the Sentinels were tricked by X-Men leader Cyclops, who told them they'd only be able to destroy mutants for good by destroying the sun, the source of all mutagenic particles on Earth. Since they did not have the firepower to destroy the sun, the Sentinels attempted to create a solar flare that would sterilize the human race, stopping them from reproducing and potentially spawning new mutants. The leading Sentinel - Number Two - had undergone mutation itself after being exposed to the sun's radiation, and was destroyed when the remaining Sentinels turned against it. The remainder of the Mark Two Sentinels were destroyed by the combined efforts of the X-Men and the Avengers.
- Appearance - Mark Two Sentinels look exactly the same as the Mark Ones, though they are taller.
- Programming - Unlike the Mark Ones, Mark Twos were programmed to protect mankind and could not harm a human in any way. Number Two and a few others could only override this directive due to mutation caused by proximity to the sun.
- Strength - Mark Twos possess greater strength than the Mark Ones, able to lift 80 tons.
- Adaptability - Mark Two Sentinels are capable of self-repair in the field and can even adapt to different attacks. They were also capable of cancelling out the abilities of the Avengers.
- Weapons - Mark Twos possess the same beam weapons as the Mark Ones. They also have extendable coils concealed in their wrists for capturing mutants.
- Scanners - Sentinels constantly scan all lifeforms within range in order to detect mutants.
- Flight - Mark Twos have jets installed in their feet for flight.