Appearing in "When Strike These Sentinels!"
- Fantastic Four
- Spider-Man (Peter Parker)
- Daredevil (Matt Murdock)
- Doctor Strange (Stephen Strange)
- Inhumans (Mentioned)
- Lockjaw (Cameo)
- Alicia Masters (Mentioned)
- Franklin Richards (Mentioned)
- Agatha Harkness (Mentioned)
- Namor the Submariner (Mentioned)
- Galactus (Mentioned)
- Black Panther (T'Challa) (Mentioned)
- Vishanti (Mentioned)
- New York State
Synopsis for "When Strike These Sentinels!"
The Fantastic Four begin are stressing out over the fact that they do not know who their mysterious attacker is. When Reed turns up nothing, he recommends that Sue go and visit their son Franklin who is in the care of Agatha Harkness at her home in Whisper Hill. Richards continues to stress to his teammates that their foe is possibly the most dangerous they have ever faced. The FF are unaware that they are being monitored by Doctor Doom from his castle in upstate New York. When one of his minions brings him the recently stolen Horn of Proteus, he orders this minion to punish himself for interrupting him. Doom then begins the next phase of his plan, deciding to be ever more cautious in order to prevent his nemesis from deducing his involvement until it it too late.
Meanwhile, Reed, Johnny, and Ben pay a visit to Xavier's School for Gifted Youngers home of the X-Men. There Reed hopes he can utilize a pair of deactivated Sentinel robots to defend his family while they are trying to determine who their mystery attacker is. As Reed joins Professor X and Marvel Girl to see the Sentinels, Johnny and Ben accept a challenge to test out the X-Men's Danger Room. As Johnny and Ben join Havok, Lorna and Iceman in the Danger Room, the Beast and Reed go over the Sentinels and activate them. The Sentinels suddenly go berserk, smashing through the Danger Room floor and attacking the heroes inside. Before the Fantastic Four and the X-Men can shut these mutant hunting robots down, they smash through the wall and escape. At that same time, Sue and Crystal are on their way to Whisper Hill when suddenly the Inhuman's dog Lockjaw materializes inside their ship and teleports Crystal away.
At that moment, the Sentinels are headed to New York City with the X-Men and Fantastic Four en route. As the Sentinels descend on the city, they also attract the attention of Spider-Man, Daredevil, and Doctor Strange who join the fight against the sinister robots. During the course of the battle Spider-Man's Spider-Sense goes wild and he manages to warn them that the Sentinels are about to explode soon enough for Doctor Strange to place a fore field around them all to protect them from the blast. Meanwhile, back at the X-Men's mansion headquarters, Professor X and Marvel Girl have to hold off the Danger Room robot known as Colosso who has also been programmed to attack them. They then quickly destroy the robot, leaving them to wonder who their attacker was.
Not far away, Doctor Doom witnesses his latest scheme go to pot, and decides that acquiring Xavier's Cerebro device is not necessary to the success of his plans and continues onto the next phase, which he hope will destroy his hated enemy Reed Richards and the rest of the Fantastic Four.
- Reed and Sue's son Franklin is said to be at the home of Agatha Harkness. At this point in time, Franklin was only recently born back in Fantastic Four Annual #6. The Fantastic Four hired Harkness as Franklin's babysitter, a role she took on from Fantastic Four #94–150. Agatha later left the Fantastic Four's employ to begin training the Scarlet Witch in the art of witchcraft in Avengers #128.
- Chronologically, the X-Men last interacted with the Fantastic Four in X-Men First Class (Vol. 2) #1 when Marvel Girl was sent on an outing with the Fantastic Four to learn from the Invisible Girl. This led to a clash with the Mad Thinker. Prior to this story, the X-Men had just recently defeated the Z'nox in X-Men #65. Professor X, Lorna and Havok were last seen in the second story of X-Men (Vol. 2) #94 where they were tested by Xavier since his return to the group. The original students: Cyclops, Marvel Girl, Iceman, Beast and Angel all previously appeared in X-Men / Spider-Man #1 where they battled Kraven the Hunter and the Blob who were secretly under the employ of Mister Sinister. While most of the X-Men are seen next issue, Havok is not seen until Fantastic Four: World's Greatest Comics Magazine #11 and Lorna until X-Men: The Hidden Years #1.
- The deactivated Sentinels seen here were likely ones captured by the X-Men following their original encounter with the mutant hunting robots in X-Men #14–16. Chronologically, the X-Men previously clashed with the Sentinels in X-Men #57–59.
- Spider-Man last encountered the Fantastic Four in Amazing Spider-Man Annual #5 where he convinced the group to allow him to borrow a ship so he could fly to Algeria to clear the name of his parents, who were branded as traitors to their country prior to their deaths. Chronologically, Peter's appearance here happened between his appearance in Amazing Adventures (Vol. 2) #3 where his employer J. Jonah Jameson tells Peter to get photos of the Black Widow and his appearance in Amazing Spider-Man #88–90 during his iconic battle with Doctor Octopus that ends in the death of Captain George Stacy.
- Daredevil last encountered the Fantastic Four when he was tricked into battling them in Fantastic Four #73 when he was tricked into fighting the group along with Spider-Man and Thor by Doctor Doom. Daredevil appears here from between his appearances in Webspinners: Tales of Spider-Man #5 when he briefly senses the Silver Surfer's rampage through New York, and Iron Man #35 when he cooled down a confrontation between Iron Man and SHIELD in his alter ego of Matt Murdock.
- Doctor Strange last worked encountered the Fantastic Four during the wedding of Reed and Sue in Fantastic Four Annual #3. His appearance here is between Webspinners: Tales of Spider-Man #5 where he also detected the Silver Surfer's rampage and his appearance in Marvel Westerns: Strange Westerns Starring the Black Rider #1 when he was entertaining the Ancient One in his home. Strange wears a mask here as he was forced to dawn a disguise following the events of Doctor Strange #177 in order to protect his identity.
- The robot Colosso was last seen being used to train the X-Men in X-Men #22, a new model was used to test the new X-Men in X-Men #94.