Wow, that's a tough one. I have several, for various reasons. These aren't presented in any real order, just thrown out there as and when I remember them.
1) Michael Jackson. Yes yes, get the Paedophile jokes out of the way, I was a fan of his, before the world had heard of Jordan Chandler. Bad was the first of his albums that I came to in the late 80s as a 4-6 year old. I liked the voice and started to listen to more and more Michael over the years. I've been through highs and lows with his music, as with the revelations about his private life, including pulling over in floods of tears the day after he died, when "I just can't stop loving you" came on my iPod. Varied music, one incredible man and one of my biggest regrets is that I never got to see him play live.
2) Alice Cooper. What would my teenage years have been like without Uncle Alice? Rock music got me at just the right time and with a combination of Alice and Queen, I was set for an interesting few years leading up to my University days, when I spent the nights combating the X Files theme at 3am with loud renditions of "It's the Little Things" at the top of my lungs, with the stereo cranked up.
The showman is truly that - the lord of the underworld, the master of disaster and the doc of shock. Guillotines, murders, grisly things happening to him on stage every night and still he comes back for more. What else could you want?
3) Iron Maiden. Up the Irons! Well, I've listened on and off to Maiden for about 2 decades, then in about 2006, I suddenly got serious with it and bought most of their albums, after becoming intoxicated with Bruce Dickinson's amazing vocals. Their inspiration led me to audition for a lead singer for a Metal Band, but we'll see if anything else comes up soon, as I didn't get that gig. I'm off to see them in Birmingham in July, so that will be awesome.
There are other bands which qualify as worthy mentions here, such as Weird Al, Red Hot Chili Peppers, Reel Big Fish, The Who, Metallica, John Denver and perhaps a few more, but, as a man with an eclectic musical taste, I've covered it in three awesome acts.