Jo Sung-jin, better known by his stage name Skull is a South Korean reggae singer. He was a member of Stony Skunk, a hip-hop and reggae duo under YG Entertainment, and a member of Skull & Haha, an entertainer duo. He is well known in the Korean Hip-Hop industry, being active since 2003. He is known for his popular features on songs such as “Acrobat” and “내 얘길 들어봐 (Listen To My Word) [A-ing]”. He is currently signed to the label he founded, Sajah Records.