Images of Marshmallow from Frozen.
Films and Television
Elsa creating Marshmallow
Marshmallow's original render
Marshmallow pretending to be a rock
Marshmallow in the post-credits scene
Marshmallow picks up the crown in the post-credits scene...
...and puts it on his head
Once Upon a Time
Gramma Tala's interpretation of the spiked monster from Lalotai which resembled Marshmallow.
What it actually looks like......
Original Concept art
Current Concept art