I'm going to attempt to chronologically list all of the Marvel characters Stan Lee had a hand in creating. Working with his genius collaborators, Stan and his team produced an insane amount of iconic characters in a roughy ten year period. (Thread)
With his younger brother, writer Larry Lieber, and Jack "the King" Kirby:
Groot
Tales to Astonish #13 (November, 1960)
With writer Lieber, and artist Kirby:
Fin Fang Foom
Strange Tales #89 (October, 1961)
With the King, Stan gives birth to the Marvel Universe:
The Fantastic Four
Fantastic Four #1 (November, 1961)
With Jack Kirby:
Mister Fantastic
Fantastic Four #1 (November, 1961)