SS501 (pronounced Double-S Five-Oh-One or Deo Beul E Seu Oh Gong Il, Hangul: 더블에스오공일, Japanese: ダブルエスオゴンイル ) is a South Korean boy band formed under the management of DSP Media, formerly known as Daesung Entertainment and DSP Entertainment. The group debuted in June 8, 2005 with five members: Kim Hyun-joong, Heo Young-saeng, Kim Kyu-jong, Park Jung-min and Kim Hyung-jun, along with their debut mini-album entitled Warning. They achieved their first number one song with "Never Again"(2005) and released their first studio album, S.T 01 Now in 2006.

In 2007, under the management of Pony Canyon, SS501 entered the Japanese-language market with their debut single Kokoro. The single debuted at the 5th spot on the Oricon chart, and moved to 3rd spot the next day. It was also chosen as an ending theme song for an anime entitled Blue Dragon. Also, they received the "Newcomer Award" by Japan Gold Disc Award in January 2008; them being the first Korean artists to receive this award.