Betty Grof

Betty was a human woman revealed to have once been the fiancée of a man named Simon Petrikov, who would much later become Ice King. She and Petrikov had a very committed relationship until Petrikov obtained an enchanted crown, which gradually began to alter his mind and body. When Petrikov put on the crown for the first time, something he did terrified Betty and caused her to leave him. Though Simon never heard from or saw her again, he desperately wished, until the crown completely corrupted his mind, to regain his sanity so that she might one day return to him. It is not known if she was killed during the Mushroom War.

Trivia

 * Simon referred to Betty as his "princess" while he still possessed some of his humanity. This may explain his obsession with Princesses.
 * In the background of the picture, there appears to be an unknown figure.
 * In one of the pictures Betty is wearing a lab coat, this might mean that she was in a field of study, such as science or medical.
 * Adam Muto says that the figure in the picture that Ice king and Betty are in is "some sort of cryptid."