Influential metal act [artist id="995"]Metallica[/artist] and groundbreaking hip-hop group [artist id="944"]Run-DMC[/artist] headline the 2009 class of [article id="1583107"]Rock and Roll Hall of Fame inductees[/article], which were announced Wednesday (January 14) at a press conference in New York.

Guitar great Jeff Beck, singer/songwriter Bobby Womack, doo-wop heavyweights Little Anthony & the Imperials and pioneering country artist Wanda Jackson were also tapped to be enshrined at this year's ceremony, which will take place April 4 at the historic Public Hall in Cleveland.

Since being founded in 1983, the Rock Hall has been criticized for being slow to recognize some bands and genres, but the induction of Metallica and Run-DMC (plus that of acts like [article id="1515054"]Black Sabbath[/article] and [article id="1554511"]Grandmaster Flash and the Furious Five[/article] in recent years) seems to indicate that is changing.

Formed in Los Angeles in 1981, Metallica rose from humble beginnings to become one of the (if not the) biggest and most influential heavy metal bands on the planet. Their 1983 debut, Kill 'Em All, is widely considered one of the first thrash-metal albums, thanks to it's blitzkrieg riffs and breakneck tempo. Their subsequent albums -- 1984's Ride the Lightning, 1986's Master of Puppets and 1988's ... And Justice for All -- saw the band expanding not just their sound, but their audience. Their self-titled 1991 album (also known as "the black album" for its iconic onyx cover) made them one of the biggest bands in the world, with a long run at #1 on the Billboard albums chart and selling a staggering 22 million copies worldwide. Last year, they released the return-to-form [article id="1592476"]Death Magnetic,[/article] which also debuted atop the Billboard charts and was one of 2008's biggest-selling albums.

Ironically, Run-DMC's video for "King of Rock" shows them wrecking havoc in the Rock and Roll Hall of Fame. The group famously formed in Hollis, Queens, in the early '80s and released their debut single, "It's Like That," in 1983. Their first three albums (1984's self-titled debut, 1985's King of Rock and 1986's Raising Hell) are considered to be among the most important hip-hop albums ever released. With their stylish dress, sample-heavy tracks and streetwise lingo, the group is often credited with bringing hip-hop to the mainstream. They gave the genre credibility when they teamed up with Aerosmith for the hit "Walk This Way," were the first rap group to be featured on the cover of Rolling Stone magazine and were one of the first hip-hop acts to have videos in constant rotation on MTV.

In 2002, Jam Master Jay -- the bedrock of the group and the man responsible for their stark soundscapes -- was [article id="1587882"]murdered in his Queens studio[/article], effectively bringing Run-DMC to an end. In 2007, MTV's Hip-Hop Brain Trust named them the Greatest Hip-Hop Group of All Time.

Nominees who weren't selected for induction in 2009 included proto-punks the Stooges, and a pair of influential funk acts, War and Chic. Artists are eligible for induction 25 years after the release of their first record, and inductees are selected by a panel of 500 "rock experts" who evaluate each candidate.