Betty

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. Simon never saw her again, and he records on video his desperate wish 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.

Appearance
Betty is a woman who appears to be in her twenties or thirties. In a picture on Simon Petrikov's wall, Betty is seen wearing glasses and a green turtle neck. In another picture, Betty is wearing a lab coat. This might suggest that she was in a field of study, such as science or medical. She has pink skin and brown-red hair.

Trivia

 * Simon referred to Betty as his princess while he still possessed some of his sanity.
 * Adam Muto stated that the figure in the picture with Simon and Betty is "some sort of cryptid."A cryptid is a creature that has been sighted before but whose existance is unconfirmed by science.
 * Pen Ward and Rebecca Sugar have stated specifically that Betty and Dr. Princess are not the same person.