Henry Rollins is an American actor, musician and social activist from Washington D.C. In addition to his old bands State of Alert, Black Flag and Rollins Band, Rollins was invited to perform guest vocals on renowned Heavy Metal guitarist and former Black Sabbath member Tony Iommi's debut 2000 release Iommi. In the Adventure Time episode "Her Parents," Rollins provided the voice of Lady Rainicorn's father, Bob Rainicorn. Henry also voiced the cookie man in "The Enchiridion!" that yells "watch where you're going!" as Finn goes to catch Princess Bubblegum from falling out of the tower.