Mr. Fantastic - Reed Richards
Reed was the son of Evelyn and Nathaniel, Reeds dad was the genius in the family and later on passed that on to his son, similar to Tony Stark he went to college when he was 14 years old.
After completing his studying he gained a government grant when he started building his spaceship, the government did allow his spaceship to take flight, that's when the know fantastic four when ahead and decided to sneak on the spaceship and take flight.
Reed did not calculate it correctly for tradition that's how they crash-landed back to earth and that's when they found out they all have superpowers, He decided to call himself Mr. Fantastic, and thus he created the Fantastic Four to be crime fighters.