Metallica was inducted into the Rock and Roll Hall of Fame in 2009.  Their drummer, Lars Ulrich, shared his opinions on this year's list of inductees and who should get in with Rolling Stone:

"I'm not gonna get into the politics or all that stuff, but I got two words to say 'Deep Purple'That's all I have to say: Deep Purple. Seriously, people, 'Deep Purple,' two simple words in the English language. But definitely, Nirvana is a no-brainer for the first year and I'm glad that Kiss is getting the long-overdue recognition that they deserved for everything that they pioneered, and then I got two words 'Deep Purple' Did I say that already?"

Deep Purple released their first album in 1968, so they were eligible for induction in 1993.  They did get nominated in 2013 and 2014, but have yet to make the cut.