Stan Lee

Stan Lee is, in essence, the creator of the Marvel Universe. Along with such greats as Jack Kirby and Steve Ditko, Lee created Iron Man, the Hulk, Thor, Black Widow, Hawkeye, the Avengers, Nick Fury, S.H.I.E.L.D., Daredevil, Groot and many, many others.

He served as a executive producer on Iron Man, The Incredible Hulk, Iron Man 2, Thor, Captain America: The First Avenger, The Avengers, Iron Man 3 ,  Thor: The Dark World, Agents of S.H.I.E.L.D., Captain America: The Winter Soldier, Guardians of the Galaxy, Avengers: Age of Ultron, Ant-Man and Doctor Strange.

He personally wrote the tie-in comic Captain America: Evil Lurks Everywhere.

Cameos
Stan Lee has played small parts in many Marvel productions.
 * Trial of the Incredible Hulk TV movie - Juror.
 * X-Men - A hot dog vendor.
 * Spider-Man - A man dodging debris from a battle between Green Goblin and Spider-Man.
 * Daredevil - A man reading the newspaper who is stopped by Matt Murdock from crossing the street.
 * Hulk - A security guard.
 * Spider-Man 2 - The man who saved a woman from debris caused by a battle between Spider-Man and Dr. Octopus.
 * Fantastic Four - Willie Lumpkin.
 * X-Men: Last Stand - A guy trying to water his lawn.
 * Spider-Man 3 - A passerby who helps Peter Parker get his head together.
 * Fantastic Four: Rise of the Silver Surfer - Himself.
 * Iron Man - Himself, mistaken for Hugh Hefner by Tony Stark.
 * The Incredible Hulk - A man poisoned by a drink laced with the Hulk's blood.
 * Iron Man 2 - The chat show host Larry King.
 * Thor - Man who tries to move Thor's hammer using his truck.
 * Captain America: The First Avenger - An elderly general.
 * The Avengers - A man being interviewed on television who didn't believe in super heroes. Also, in a deleted scene, he told Steve to ask the waitress for her number.
 * The Amazing Spider-Man - Librarian.
 * Iron Man 3 - Beauty pageant judge.
 * Thor: The Dark World - Mental patient.
 * Agents of S.H.I.E.L.D. episode T.R.A.C.K.S. - Train passenger.
 * Captain America: The Winter Soldier - Smithsonian security guard.
 * The Amazing Spider-Man 2 - Graduation spectator.
 * X-Men: Days of Future Past- A man who escapes from Magneto's attack.