While in space, a group of scientists are exposed to cosmic radiation due to an explosion that leaves them with superpowers. The group becomes known as The Fantastic Four and keeps evil at bay while figuring out a way to return themselves back to normal. Everyone chose David Tennant for Reed Richards but this fancast may surprise you.
Ewan McGregor as Reed Richards/Mr. Fantastic
Reed Richards, the founding member of the Fantastic Four, is a scientific genius that attended several colleges by the age of 20. At Empire State University he met Ben Grimm, star football player, and Susan Storm, the love of his life. Reed had already begun designing a starship capable of traveling in hyperspace. Sharing his plans with his new roommate, Grimm jokingly volunteered to pilot the craft. Sue also made a bet with Reed that if he ever finished she would accompany him on the trip. As a result of the cosmic explosion he gained the power to stretch and contort his body into any shape imaginable.
Alice Eve as Susanne 'Susan' Storm/The Invisible Woman
*Props to Shadow11* With the subtle name change to 'Sussane' I keep trying to distance myself from the first two F4 movies which is difficult. Alice could pull off an amazing Susan Storm in terms of her charm,power and intellect. Susan promised her future husband Reed Richards in college that if he completed his spacecraft she would accompany him on the trip. During the cosmic explosion she gained the power to turn herself and other objects invisible while also being able to manipulate objects and people via an invisible force field.
Michael B. Jordan as Johnny Storm/The Human Torch
If you have a problem, work it out in therapy. I remember seeing this kid on Ridiculousness with Rob Dyrdek and he just oozed charisma and confidence and he was pretty funny too. Then fast foward some months later and I hear he's playing Johnny Storm in the F4 reboot and I was truly excited about that choice even before I thought to myself "Wait Human Torch wasn't black.". Regardless, this is a gret chance at reinvention of the character that could even top Chris Evans in the role. A fresh high school graduate and half-brother of Susan Storm, Johnny is well-known for being hard-headed and sometimes a slacker. He was talked into coming on the space exploration mission by his sister Susan. As a result he gained the power to engulf his entire body in flames, is able to fly, can absorb fire harmlessly into his own body, and can control any nearby fire by sheer force of will. "Flame on!", which the Torch customarily shouts when activating his full-body flame effect, has become his catchphrase.
A star football player that jokingly agreed to pilot his best friend's trip to outer space. Exposure to a cosmic explosion made him a rocky, orange giant with incredible strength. Known for his famous yell "It's clobberin' time" which he used in his football games, he brought that aspect of his personality with him while in the Fantastic Four.
Johnny Depp as Victor Von Doom/Dr. Doom
The man who funded Richards' spacecraft for exploration, Von Doom himself was exposed to the cosmix explosion giving him technopathy and electromagnetic manipulation. The explosion, however, scarred him severly and he was bedridden for several months. With his company bankrupt he blamed Richards and used the last of his profits to have a suit forged for him.
Rachel Nichols as Carol Danvers/Ms. Marvel
The love intrest of Johnny Storm and classmate/friend of his half sister Sue, she was Johnny's reason for going on the spacecraft mission in the first place. Ironically, she seemed to be the only one who did not gain any powers due to the cosmic explosion but later was seen to possess superhuman strength, speed, stamina, and durability along with energy projection and absorbtion.