Task: Question Answering
Input (English): Passage: As Opeth's primary songwriter and lyricist, vocalist/guitarist Mikael Åkerfeldt heads the direction of Opeth's sound. He was influenced at a young age by the 1970s progressive rock bands King Crimson, Yes, Genesis, Camel, P.F.M., Hawkwind, and Gracious, and by heavy metal bands such as Iron Maiden, Slayer, Death, Black Sabbath, Deep Purple, Celtic Frost, King Diamond, Morbid Angel, Voivod, and, most importantly, Judas Priest. Åkerfeldt considers Judas Priest's Sad Wings of Destiny (1976) the best metal album of all time, and notes that there was a time when he listened only to Judas Priest. While warming up before Opeth concerts, Åkerfeldt frequently sings "Here Come the Tears" from Judas Priest's third album Sin After Sin (1977). Åkerfeldt later discovered progressive rock and folk music, both of which had a profound impact on the sound of the band.Opeth's distinct sound mixes death metal with progressive rock. Steve Huey of AllMusic refers to Opeth's "epic, progressive death metal style". Ryan Ogle of Blabbermouth described Opeth's sound as incorporating "the likes of folk, funk, blues, '70s rock, goth and a laundry list of other sonic oddities into their trademark progressive death style." In his review of Opeth's 2001 album Blackwater Park, AllMusic's Eduardo Rivadavia wrote, "Tracks start and finish in seemingly arbitrary fashion, usually traversing ample musical terrain, including acoustic guitar and solo piano passages, ambient soundscapes, stoner rock grooves, and Eastern-tinged melodies—any of which are subject to savage punctuations of death metal fury at any given moment." Åkerfeldt commented on the diversity of Opeth's music:
I don't see the point of playing in a band and going just one way when you can do everything. It would be impossible for us to play just death metal; that is our roots, but we are now a mishmash of everything, and not purists to any form of music. It's impossible for us to do that, and quite frankly I would think of it as boring to be in a band that plays just metal music. We're not afraid to experiment, or to be caught with our pants down, so to speak. That's what keeps us going.
More recently, Opeth have abandoned their death metal sound resulting in a mellower progressive rock sound. When talking about Heritage, guitarist Fredrik Åkesson stated:
In the beginning it took me a little while to get used to the new idea of the sound, not having any screaming vocals and stuff like that.  But I think the album was necessary for us to do. Maybe the band wouldn't have continued if we hadn't done Heritage.  I think the old Opeth fans understand this album. There's always going to be some haters, but you can't be loved by everyone. Opeth has always been about not repeating ourself. A lot of people don't think Heritage is metal but I think it's metal to go somewhere people don't expect. It doesn't mean we're not embracing the past sound of Opeth. 
Question: What is the last name of the person who was influenced by P.F.M.?
Output (English): Åkerfeldt.