Everyone and their mother know the core four members of the Fantastic Four; Reed Richard's Mr Fantastic, Sue Storm's Invisible Woman, Johnny Storm's Human Torch and Ben Grimm's Thing. Over the years, every member of the team has been subbed out for various narrative reasons, but mostly to shake up the team roster.
There isn't much the team hasn't done. From space travel, to undersea adventures, even reaching into the realms of mysticism. So, it is unsurprising that the FF has reflected these aspects with various members of the larger Marvel universe lending their support across the team's long history. As Dan Slott highlighted in the third issue of his current Fantastic Four run, Marvel's first family has an expansive roster of heroes they can trust to join them in their hours of need.
With a wide selection of Marvel characters to choose from, over the last 80 years the Fantastic Four has been home to many heroes. From street level characters like Spider-Man and Luke Cage, to Inhuman and Wakandan royalty and the Heralds of Galactus, the Fantastic Four has housed a wide variety of eclectic characters.
10. Luke Cage
Known as Power Man at the time, Mr Fantastic hired Luke Cage to join the Fantastic Four. His time on the team only lasted three issues (#168-#170) back in 1976. Reed hired him to replace the Thing after Ben Grimm temporarily lost his powers and became a 'normal' man.
On his first mission with the Fantastic Four, they fought the Wrecker while Ben wallowed about his lost place on the team. Later, the Puppet Master took control of Cage, forcing him to battle the team. Ben then takes an exo-suit (designed to look like his previous rocky form) and the two clashed until the Puppet Master's control over Luke was broken, freeing the Hero for Hire.
Even though his tenure on the team was short-lived, Luke Cage helped remind Ben Grimm that he was part of the Fantastic Four family with or without his powers. Also, in Luke's charitable fashion, Reed revealed that Luke donated his entire FF salary to charity.