The Fantastic Four are the ideological center of Marvel Comics. Stan Lee and Jack Kirby filled their signature comic with boundless creativity, dynamic action and inspired characters that paved a solid foundation for the House of Ideas. While their star has faded some in recent years, the Fantastic Four’s adventures have introduced a plethora of Marvel’s most noteworthy concepts and characters in the team’s 55-year history.

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In that half-century, Marvel’s First Family has grown quite close to some of the characters they’ve met along the way. Naturally, some of the heroes even joined the team whenever there was an open spot on the roster. Now, CBR takes a look back at some of the Fantastic Four’s strangest members. These characters aren’t inherently strange, but they’re all an odd fit, to some degree, within the Fantastic Four.

16 Honorable Mention: Doctor Doom and the Future Foundation

Under Jonathan Hickman and Steve Epting, the Fantastic Four evolved into the Future Foundation in 2011. After the (temporary) death of Human Torch, Mr. Fantastic set up the organization to ensure a better future by training some of the Marvel Universe’s brightest youth in one of Marvel’s few recent kid-centric titles. In the pages of “FF,” the super-powered think tank expanded to include some unlikely members, like former Power Pack kid-hero Alex Power and even the Fantastic Four’s nemesis Doctor Doom. After Marvel’s 2015 crossover “Secret Wars,” the Future Foundation was sent off to help rebuild the multiverse. Like the Fantastic Four, they haven’t appeared since the end of that story.

Even outside of the Future Foundation, the Fantastic Four have always surrounded themselves with friendly faces. While these friends and allies have played important roles, many of them never technically served on the Fantastic Four. Despite their lack of official membership status, the Future Foundation and the Four’s various allies still warrant this honorable mention.

15 Luke Cage

After a decade as an Avenger and his own Netflix show, Luke Cage is one of the most prominent characters in Marvel’s modern era. In 1976, this wasn’t quite the case. When Cage was still called Power Man and wore a tiara, he briefly joined the team as a replacement for a de-powered Ben Grimm in “Fantastic Four” # 168. Writer Roy Thomas had helped create Cage four years previously, and hadn’t written the character extensively until this point.

During his three-issue membership, Luke Cage spent most of his time fighting the rest of the team while under the control of the Puppet Master, one of the team’s oldest foes. After donning a robotic Thing exo-suit created by Mr. Fantastic, Ben defeated Power Man and took back his spot on the team. During his brief time there, Cage even took a salary. Although he donated it to charity, Cage still lived up to his former title as a “hero for hire.”

14 Crystal

Although she possessed considerable elemental powers, Crystal was originally created by Stan Lee and Jack Kirby to be a romantic interest for the Human Torch, Johnny Storm. When the Invisible Woman went on maternity leave, the Inhuman officially joined the team in 1968’s “Fantastic Four” #81, becoming the team’s first new recruit. After Sue Storm returned, Crystal stayed with the team for the duration of Lee and Kirby’s run. Shortly after Kirby left the title, Crystal was written out in “Fantastic Four” #105, due to her inability to survive in Earth’s polluted atmosphere.

After her time with the team, Crystal split up with Johnny, returned to the Inhumans and married the Avenger Quicksilver. When Mr. Fantastic, Reed Richards and Sue took a leave of absence to raise their son Franklin in 1987, Crystal rejoined the team exactly 200 issues after she left. She has become a big player in Marvel’s recent Inhumans comics. As a member of the Inhuman Royal Family, Crystal seems likely to appear in Marvel’s ”Inhumans” television show, set to debut in 2017.

13 Ant-Man

After floating around the Marvel Universe for most of the 1980s, the second Ant-Man, Scott Lang, found a home in Tom DeFalco and Paul Ryan’s divisive “Fantastic Four” run in the mid-1990s. When Mr. Fantastic was thought dead, Lang was hired by the team at Tony Stark’s recommendation in 1994’s “Fantastic Four” #384. As the team’s technological consultant, Scott and his young daughter Cassie lived at Four Freedoms Plaza with the rest of the Four. When Reed was rescued after being held prisoner by his grandson from a parallel universe, Hyperstorm, Lang unofficially stepped down from the team but stayed on as a close associate.

Although his knowledge base isn’t as broad as Mr. Fantastic’s, Ant-Man served as the team’s resident genius on two more occasions. The first came in 2001’s “Fantastic Four” #42, when the Human Torch formed a makeshift Fantastic Four to rescue the original team from the Negative Zone. In 2013’s “FF” series, Lang replaced Reed again in a substitute Fantastic Four team and led the Future Foundation while the original team was time-traveling.

12 Medusa

Medusa, the Queen of the Inhumans, originally encountered the Fantastic Four as an amnesiac member of the villainous Frightful Four. After she regained her memories, the hero with prehensile hair resumed her role co-leading the Inhumans alongside her husband Black Bolt. While Reed and Sue were separated, Medusa worked closely with the team before officially joining in 1973’s “Fantastic Four” #132. During most of Gerry Conway’s time writing the title, she served as the Inhumans’ ambassador to the outside world as Reed and Sue reconciled and took care of their comatose son.

After Sue rejoined the team full-time in 1975, Medusa left to resume her duties with the Inhumans. She remained a close ally of the Fantastic Four and replaced Sue again in the substitute team featured in 2013’s “FF.” More recently, she started dating the Human Torch, her sister Crystal’s ex-boyfriend, and has taken on a prominent role in the Marvel Universe. Like Crystal, Medusa will almost certainly appear with the rest of the Inhuman Royal Family in the upcoming “Inhumans” show.

11 Nova

While dating Johnny Storm, Broadway actor Frankie Raye discovered that she had fire powers similar to his. She was the stepdaughter of Phineas T. Horton who, unbeknownst to her, had created the original Human Torch android. After being exposed to some chemicals, she developed the ability to make and control fire. Fearing for her safety, Horton put her in a power-suppressing suit and hypnotized her into forgetting about her abilities. After re-learning about her powers, she became another Human Torch and a probationary member of the team in 1982’s “Fantastic Four” #238.

After a short time with the team, Frankie offered to become the new herald of Galactus to save the Earth in a memorable John Byrne story. Galactus accepted her offer and gave her the Power Cosmic. Now known as the ultra-powerful Nova, she left Earth and found worlds for Galactus to devour. She eventually befriended Galactus’ former herald, the Silver Surfer, who turned her against their old master. In 1992, Nova’s flame was snuffed out by Morg, another herald of Galactus. After almost two decades, she came back to life in the 2010 miniseries “Heralds.”

10 She-Hulk

As a member of some incarnation of the Fantastic Four for over 50 issues, She-Hulk is easily the team’s most frequent substitute member. After Thing decided to stay on the alien Battleworld at the end of 1985’s “Marvel Super Heroes Secret Wars,” he asked She-Hulk to be his replacement on the team. With her combination of strength, assertiveness and good humor, the character was a good, somewhat unlikely fit for the team during John Byrne’s run on the title. Unlike her cousin Bruce Banner, She-Hulk maintained her intelligence in her “hulked-out" form, and inadvertently got stuck that way during her time with the Fantastic Four.

When Ben returned to Earth, She-Hulk ended her time with the team. She helped him come to terms with the engagement of Johnny and “Alicia Masters,” who was secretly an alien Skrull named Lyja who was posing as Ben’s longtime girlfriend. Besides her occasional stints as an Avenger, She-Hulk would go on to star in a light-hearted solo series, partially written and drawn by Byrne. In 2013, She-Hulk would once again take Thing’s spot on the roster for the substitute Fantastic Four team featured in “FF.”

9 Black Panther and Storm

In the wake of 2006’s “Civil War,” Reed and Sue took another leave of absence to work out some marital issues. While they were on their “second honeymoon,” their spots on the team were given to longtime “Fantastic Four” ally Black Panther and his then-wife Storm in 2007’s “Fantastic Four” #543. During this period, Black Panther was already in New York to help ease international relations in the wake of the Super-Human Registration Act.

This version of the Fantastic Four was the team for most of Dwayne McDuffie and Paul Pelletier’s well-regarded run on the title. After seven issues away, Reed and Sue returned to their regular slots on the team, while Black Panther and Storm’s marriage was eventually annulled. In the wake of several recent catastrophes, Storm took leadership of the X-Men. Black Panther, meanwhile, played an increasingly large role in the Marvel Universe in the lead-up to 2015’s “Secret Wars.” He’s remained one of the company’s most visible characters with his highly-anticipated solo film set for 2018.

8 She-Thing

Despite being a member of the Fantastic Four for four years, Sharon Ventura has become a footnote in the team’s history, often going years between appearances. Sharon started out as the second Ms. Marvel, a super-strong hero who met the Thing during his time in a super-powered wrestling league. When Reed and Sue briefly retired in 1987, she joined the team along with Crystal in “Fantastic Four” #306.

On one of her early adventures with the team, she became She-Thing after being bombarded by cosmic rays. Originally introduced to the team by Steve Englehart and John Buscema, Sharon continued to serve with them long after Reed and Sue returned to the title. After seeking Doctor Doom’s help curing her, she double-crossed the Latverian dictator, who briefly transformed her into an even more monstrous form that drove her insane. After fading into background roles, She-Thing returned as an antagonist in one of the last “Fantastic Four” stories before the title went on its ongoing extended hiatus.

7 Namorita

While Namor the Sub-Mariner has been an ally of the Fantastic Four since its earliest days, he’s never actually served as a member of the team. The same can’t be said for his cousin Namorita. The former New Warrior joined Human Torch’s makeshift Fantastic Four in 2001’s “Fantastic Four” #42 by Carlos Pacheco, Jeph Loeb, Rafael Mann and Stuart Immonen. Along with She-Hulk and Ant Man, this version served for three issues while the rest of the team had been trapped in the Negative Zone by a mysterious group called the Gideon Trust.

When that version of the team disbanded, Namorita stayed close to the Fantastic Four while she dated Johnny. After the publicity-attracting couple broke up, Namorita returned to Atlantis and later the New Warriors. She was killed with the rest of the Warriors by the exploding villain Nitro in the 2006 incident that kicked off Marvel’s “Civil War," but was later revived with help from a time-traveling Nova, a teammate from her days with the New Warriors.

6 H.E.R.B.I.E.

The robot known as Humanoid Experimental Robot, B-Type, Integrated Electronics, or H.E.R.B.I.E. for short, never actually served as a member of the Fantastic Four in their comic. H.E.R.B.I.E. was a member of the team in the infamous 1978 cartoon, “The New Fantastic Four.” Created by Stan Lee and Jack Kirby, H.E.R.B.I.E. replaced the Human Torch on the NBC animated series since the television rights to the Human Torch had already been sold to Universal Studios.

Shortly after his televised debut, H.E.R.B.I.E. made his first comic book appearance in Marv Wolfman and John Byrne’s “Fantastic Four” #209 as a robotic creation of Mr. Fantastic. Although he has appeared infrequently over the years, H.E.R.B.I.E. has become something of an inside joke among comic fans. More recently, H.E.R.B.I.E. has been portrayed as a robotic guardian for the Richards kids, Franklin and Valeria. In Chris Eliopoulos’s out-of-continuity series “Franklin Richards: Son of a Genius,” H.E.R.B.I.E. had his most prominent role as the mischievous Franklin’s sidekick and protector.

5 Flux

In one of Marvel’s more personal stories in recent memory, Dennis Sykes was force-fed toxic medical waste that gave him both fatal cancer and matter-warping powers at the same time. In the 2010 miniseries “1 Month 2 Live,” a host of Marvel creators like Rick Remender, Stuart Moore, Shane White and John Ostrander showed the heroic deeds Sykes performed during the final month of his life.

After being initially diagnosed by Mr. Fantastic, Sykes was given the name Flux and officially recruited by the Fantastic Four for a deep space mission. Ironically, Ego the Living Planet had been driven into a star-consuming feeding frenzy by a cancerous entity growing inside him. Flux used his newfound powers to heal the sentient planet before returning back to Earth. After being given an honorary membership on the team, he continued to help out Marvel’s heroic community and was ultimately invited to join the Avengers shortly before his death.

4 Franklin and Valeria Richards

Despite their young age, Franklin and his sister Valeria Richards proved to be invaluable assets to their family’s team. Franklin was a mutant and one of the most powerful beings in the Marvel Universe, with a nearly unlimited amount of reality warping power. In one of the earliest exhibitions of his power, Franklin saved his unborn sister by sending her into an alternate reality where she was raised by Doctor Doom. After a teenage version of that Valeria helped the Four of the main Marvel Universe, Valeria was literally reborn as an infant thanks to Franklin’s powers.

The young Valeria quickly became one of the smartest people in the Marvel Universe, with an intellect that rivals (and in many cases, even surpasses) her father’s super-genius. After the siblings defended the Fantastic Four’s home in 2008’s crossover “Secret Invasion,” they took on more active roles with the team. These two characters were the central members of the Future Foundation and are currently rebuilding the Marvel multiverse in the wake of 2015’s “Secret Wars.”

3 Miss Thing

When she was drafted into the Fantastic Four, Darla Deering was just a regular pop star. While she was dating the Human Torch, he chose her as his last-minute replacement when the core Four went time-traveling in 2013’s “FF” #1. Since she didn’t have any powers, she was given one of the Thing’s old exo-suits from when he was depowered and subsequently named herself Miss Thing. In Matt Fraction and Mike Allred’s delightfully kooky “FF,” she also served as a member of the Future Foundation and briefly had a relationship with Scott Lang’s Ant-Man.

In a nod to the 1979 cartoon “Fred and Barney Meet the Thing,” the Thing exoskeleton collapsed down into two “Thing Rings.” Like that cartoon’s Benjy Grimm, she would put the two rings together and say “Thing Rings, do your thing” to bring forth her rocky exterior. Since her team disbanded, Darla has popped up as a supporting character in Lang’s solo title “Astonishing Ant-Man.”

2 Lyja

Long before Marvel’s 2008 crossover “Secret Invasion,” Lyja, a shape-shifting Skrull, was sent to infiltrate the Fantastic Four. She accomplished this by posing as the Thing’s longtime girlfriend, Alicia Masters, and started a relationship with the Human Torch while the Thing was on Battleworld. After she and Johnny were married, her true nature as a Skrull was revealed. Despite the complex nature of their relationship, she still had feelings for her husband and helped the Fantastic Four rescue the real Alicia Masters.

After Johnny left the team for a short time in 1995, Lyja took his place in “Fantastic Four” #403. When the Human Torch and Mr. Fantastic returned to the team a few months later, she stepped down along with Ant-Man and became an ally of the team once more. Tom DeFalco and Paul Ryan introduced Lyja to the team as a way to undo the years-old marriage between Alicia Masters and the Human Torch, which they said felt a little too cruel to Ben and seemed out-of-character for both parties. Lyja more recently appeared during the Skrull-focused “Secret Invasion” story, when she aided the Four once again.

1 New Fantastic Four

In one of “Fantastic Four’s” most inspired commercial and creative moments, Walt Simonson and Art Adams created a temporary Fantastic Four that included Spider-Man, Wolverine, Ghost Rider and the Hulk. After being tricked by a Skrull posing as Invisible Woman, this group of Marvel’s most popular characters gathered together for a light-hearted adventure involving Monster Island and the Mole Man, who the original Four battled in their very first adventure.

Although he officially joined during this fondly-remembered tale, Spider-Man had been one of the Fantastic Four’s closest allies since their earliest days. In 1963’s “Amazing Spider-Man” #1, Spider-Man tried to join the Fantastic Four to earn some money, but left disappointed after learning that they were a non-profit organization. After Human Torch’s presumed death in 2011, he took his best friend’s place on the team as it morphed into the Future Foundation. After a not-dead Johnny returned from being trapped in the Negative Zone, Spider-Man left the team officially but remained a surrogate member of Marvel’s First Family.

Who's your favorite member of the Fantastic Four's extended family? Let us know in the comments!