There aren't very many instantly recognizable metal vocalists these days - the extreme style of death metal vocals ironically has the effect of making too many frontmen sound the same. But once upon a time, metal singers were not only actually singing, but doing so in highly individualistic, iconic styles, and one such icon is Kim Bendix Petersen, better known as King Diamond. His piercing upper register is astonishing and unmistakable, putting him in the company of classic frontmen like Judas Priest's Rob Halford, Iron Maiden's Bruce Dickinson, Ronnie James Dio and Geoff Tate, and he turns 56 today, June 14.

Diamond first emerged as singer for Mercyful Fate, who released two undeniably classic albums on Roadrunner - 1983's Melissa and 1984's Don't Break the Oath. When that band broke up, the King wasted no time in going solo, and he released a string of albums on Roadrunner: 1986's Fatal Portrait, 1987's Abigail, 1988's Them, 1989's Conspiracy, and 1990's The Eye. Even after leaving the label, he remained active throughout the '90s, issuing seven more studio albums under his own name between 1995 and 2007, including 2002's Abigail II: The Revenge, and also reviving Mercyful Fate for several more releases. Throughout his career, he's been known not just for his amazing vocal talents, but for his striking face paint and overall theatrical presentation. A King Diamond performance is more than a rock concert - it's a show.

Though he's had some recent health problems, King Diamond is still very much with us. He appeared with Metallica during their 30th anniversary concerts in December 2011, and performed a comeback set at the Sweden Rock Festival earlier this month. So Happy Birthday to King Diamond - long may he reign!