Who is Kangta?

This was supposed to be a funny Kangta compilation, but it turned into an educational vid instead. Whoops. Vid sources: Candy MV:    • [HQ]H.O.T - Candy MV   Polaris:    • 음악캠프 - Kang Ta - Polaris, 강타 - 북극성, Music ...   Happiness:    • H.O.T - Happiness, H.O.T - 행복, MBC Top Mus...   Sorrow:    • N.R.G  - Sorrow, 엔알지 - 비(悲), Music Camp 20...   Age of Peace:    • H.O.T - Age Of Peace (3D Movie) Trailer   Radio Show:    • SECHSKIES A waiting room for fear   I Swear:    • S 에스 'I Swear' MV   My Old Little Boy:    • 강타, 2주간 집에 머물겠다는 토니 단칼에 거절 “안 돼!” @미운 우리 새...   Date w/Kyuhyun:    • Guerrilla Date with Kyuhyun, Kangta [Enter...   ICSYV4:    • [ENGSUB] Jun A.C.E at ICSYV4 cut   I Live Alone:    • 【TVPP】EXO - At SM building.. Kangta vs EXO...