The term SEUSS CHARACTER refers to characters created by the famous children's author Dr. Seuss. The five characters mentioned in the crossword solutions are the Lorax (5 letters), Sam (3 letters), the Grinch (6 letters), Horton (6 letters), and Sam-I-Am (6 letters). The Lorax is a mustachioed creature who speaks for the trees, Sam is a character from the book 'Green Eggs and Ham', the Grinch is a green creature who hates Christmas, Horton is an elephant who hears a Who, and Sam-I-Am is a character from the book 'Green Eggs and Ham' who tries to convince the other character to try the dish.