Vanilla Ice got me into Rap (yes I still listen to him to this day) Dr Dre got me into harder Rap.
First big alternative rock band I got into was Green Day but Disturbed locked me into the Genre.
Older rick would have to be AC/DC or Metallica
Pop would be Michael Jackson.
I listen to damn near ever genre so I could list someone for everything. Electronica: bjork, Horrorcore: ICP, Punk: Wheatus, etc