Cartoonist – Someone who writes and illustrates their own stories or jokes.
Penciler – A person who illustrates a story in pencil.
Inker – Someone who go over the pencils with ink and adds shadows.
Colorist – A person who adds color to the comic.
Letterer – Someone who adds the text and balloons to the comic.
Illustrator – A person who does more than one or all of the above jobs (penciler, inker, colorist, letterer).