Beauty Mark Beth is a version of Beth with a prominent beauty mark on her face.
After Doofus Jerry overthrew the Council of Ricks and took control of The Citadel, he had several Beths brought to him to be his harem. Beauty Mark Beth was one of the Beths who also kept closest to him, despite his mad behavior. Even though they never left his side, they could never substitute for the Beth he first met. After Doofus Jerry's death, she presumably was returned to her dimension.