Park Sang-hyun, known by his stage name Thunder, is a South Korean singer, songwriter, actor and model. He is a former member of South Korean boy band MBLAQ. On December 16, 2014, it was announced that he had departed from the group to focus on studying music. He signed with Mystic Entertainment's music label APOP on February 11, 2015 and released his debut extended play on December 7, 2016.

MBLAQ is a South Korean boy band created by South Korean singer Rain under J. Tune Camp. The group consists of Seungho, G.O, and Mir, and formerly Lee Joon and Thunder. The group debuted on October 15, 2009, at Rain's Legend of Rainism concert.