Iron Butterfly

Iron Butterfly will forever be a part of the rock pantheon on the strength of their signature song "In-A-Gadda-Da-Vida", the title track from their 1968 second album. A gargantuan piece of primordial riff-rock, it took up the entire first side of the LP, but still became a huge success, epic-length drum solo and all. With their heavy guitars, spooky organ, and air of mystery, they were the missing link between the Doors and Led Zeppelin, effectively building a bridge between '60s psychedelia and '70s hard rock.