Although Stan Lee and Jack Kirby created the X-Men, not a lot of the villains they created for the mutant heroes became as iconic. Sure, there’s Magneto and Juggernaut. But aside from those characters, the most important X-Men villains to come from Lee and Kirby are the robotic Sentinels. That’s because these giant robots, while looking super cool and menacing (thank you Jack Kirby) also represent humanity’s hatred for anything that’s different. This is why they’ve lasted through so many iterations of the X-Men, from comics to cartoons to the big screen. Once again, they’re making life miserable for the students of Xavier’s School in X-Men ’97 on Disney+. Here is a brief history of the Sentinels in comics and beyond.

The X-Men attack Xavier's School in 2004's Astonishing X-Men, art by John Cassaday.
Marvel Comics

The First X-Men Appearance of the Sentinels

First appearing in 1965’s X-Men #14, the Sentinels were introduced as the creation of a scientist named Bolivar Trask. Believing mutants would rise up and wipe out the human race, Trask used his genius in cybernetics to create giant robots. Machines with the ability to detect mutant genetics, and capture or kill them. Sentinels ranged from 20-30 feet tall to slightly larger than human size. These robots had faulty programming and believed the only way to protect humans from mutants was to rule them.

Marvel Comics

Over a three-issue storyline, the X-Men discover that the Sentinels are created by a Master Mold. This was an even bigger Sentinel designed with software to create more Sentinels. Trask is horrified that what he used to supposedly help mankind against mutants would have been their destruction as well. He died destroying the Master Mold. The mutant race was safe from Sentinels—but only for a time. 

The Sentinels Evolve Into the X-Men’s Most Dangerous Foe

Marvel Comics

Over the following years, the X-Men fought new iterations of Sentinels. Bolivar Trask’s son Larry Trask picked up his father’s work. He created the Mark II Sentinels, new models that could adapt and counteract almost any superpower. Years later, another mutant hater, a robotics scientist named Stephen Lang, adapted Trask’s technology and created the Mark III Sentinels. He also created the so-called ‘X-Sentinels,’ which were androids that mimicked the X-Men themselves. And it was actually a mutant, the Hellfire Club’s Sebastian Shaw, who created the Mark IV-VII Sentinels.

“Days of Future Past” Shows the Sentinels at their Most Lethal

Marvel Comics

The true indicator of how much of a threat the Sentinels were was in Chris Claremont and John Byrne’s iconic two-part storyline, “Days of Future Past.” Running in 1981’s Uncanny X-Men #141-142, that story showed us a future in which Sentinels became fully sentient AI and took control of North America. They hunted mutants nearly to extinction, forcing the team to send one of their own into the past. All in order to help the X-Men stop this horrible future from ever happening. This story cemented Sentinels as the X-Men’s ultimate foe, and provided the basis for a two-part storyline in X-Men: The Animated series. Not to mention the live-action 2014 film of the same name.

Modern-Day Sentinels Almost Decimate the X-Men

Marvel Comics

In the “present time,” a Sentinel did massive damage to the mutant race. A giant “Wild Sentinel,” built by a lost Master Mold and made of metal junk, surfaced in South America. They were built in the service of Charles Xavier’s evil twin Cassandra Nova. She ordered them to obliterate the mutant island of Genosha in 2001’s New X-Men #114, killing 16 million mutants. Later, when the mutant population was decimated by 98%, human-piloted Sentinels were introduced. As a representative of humankind’s hatred of mutants, the Sentinels remained a perpetual thorn in the side of the X-Men.

Nimrod Is the Ultimate Evolution of the Sentinel

Marvel Comics

As the ‘80s and ‘90s storylines progressed, so did the Sentinels. In the ’80s, readers were introduced to Nimrod, an advanced Sentinel from the future that came back to the present. Hailing from the “Days of Future Past” timeline, Nimrod can transform to look like anyone. Also, its consciousness can extend outside its physical form. A Nimrod unit and a Master Mold mystically fused into the android Bastion, who was a major enemy in the ’90s era. In the most recent X-Men era, Nimrod came online in the present day. It emerged in the service of the mutant-hating organization called Orchis. The product of a powerful Mother Mold, a Sentinel that creates Master Molds, Nimrod has recently set back the mutant cause years, essentially running them out of their homeland of Krakoa.

Sentinel Powers and Abilities

The Sentinels initially had super strength, the power of flight, and energy blasts. They also had a program allowing them to detect and target anyone with an X-gene. The Mark II Sentinels had more advanced programming, allowing them to adapt to various mutant powers they encountered. They could also self-repair. When one of the Sentinels evolved and developed the power to teleport, it was considered a mutation, and so it self-destructed. Versions of the Sentinels from the future who time-traveled to the present were even more advanced, and could even reconstitute after being shattered to pieces, and download their consciousness to other computer systems.

The Sentinels in X-Men: The Animated Series


The Sentinels first appeared as the antagonists in the very first episode of X-Men: The Animated Series in 1992. In that two-part opener, “Night of the Sentinels,” the deadly robots were shown as the embodiment of mankind’s hatred of mutants. They were utilized by government forces to track down and contain mutants. They largely kept their comic book origins and design, and kept reappearing throughout the show’s five-season run. Sentinels also appeared in later X-Men animated shows, like X-Men: Evolution, and Wolverine and the X-Men.

The Live-Action X-Men Films’ Version of Sentinels

Twentieth Century Films

Despite being in several early drafts of the first two X-Men movies, their robot adversaries did not appear in the final films. We saw a glimpse of a Sentinel in the Danger Room sequence in X-Men: The Last Stand, but they weren’t the real deal, just a training hologram. Sentinels finally made their big screen debut in X-Men: Days of Future Past. In that 2014 film, Sentinels drove the entire plot. We learned that Bolivar Trask invented them as more rudimentary mutant-hunting robots in the ‘70s, reflecting their comic book aesthetics. We also saw future Sentinels in that film, which were highly advanced thinking machines that could replicate mutant powers. They had also taken over the world, making it a dystopian hellscape. We glimpsed the movie universe’s Mark I Sentinels one last time very briefly in a Danger Room sequence at the end of X-Men: Apocalypse.

The Sentinels in X-Men ’97

Marvel Animation

In the first episode of X-Men ’97, we learn that a secret army of Sentinels is being constructed in the Sahara desert, created by Bolivar Trask and Henry Gyrich. The X-Men arrive, and take them all out in an amazing action scene. Storm in particular does some damage. In an echo of the original cartoon, the revival series is using the Sentinels early on, hammering home the notion that these robots are the mutant race’s ultimate enemy. We’ll see as the first season of X-Men ’97 unfolds if more Sentinels are still out there, waiting to say “Halt Mutant!” in their eerie robotic voices.

Originally published on March 18, 2024.