It would be too challenging for me to pick just one so here is my list:

• Jim Henson (Muppets, Sesame Street, Fraggle Rock, etc.)
• Walt Disney (7 plane camera, theme parks, cartoons and movies)
• Dr. Seuss (political cartoons, advertisements, children's books, animated shorts)
• Chuck Jones (Road Runner & Wile E. Coyote, Pepe le Pew, Marvin Martian, animated Tom & Jerry and helped animated Dr. Seuss shorts)
• Tex Avery (Bugs Bunny, Daffy Ducky, Porky Pig and Droopy)

Going a bit further back

• Benjamin Franklin
  
• Voltaire

• Leonardo Da Vinci

I know it is quite a weird mix of people, and many of their were illustrators / animators. However, I feel like the best way to create the future is to spend time in the unknown (imagination) and those people had it in spades.