Two Witch Sisters

Niki Hyun Yang (born in Seoul, South Korea as Hyun Jeong Yang; Korean: 양현정; RR: Yang Hyeonjeong, June 8, 1985) is a South Korean animator, writer, storyboard artist, and voice actress. After graduating from Hongik University and then CalArts, she became one of the storyboard artists of Family Guy before moving to Frederator Studios. She is best known for voicing BMO and Lady Rainicorn on the Cartoon Network series Adventure Time.