Best Growling/Screaming Part.

Another vote for Demon of the Fall, but a different part: on "in the blink of an eye," his growl on "eye" rattles in this fantastic way. He was sick during recording, so perhaps phlegm is to blame (or thank)? :)
 
I'll go out on a limb (stem?) and say the end of The Apostle in Triumph..

With the opening of souls and immortality and embracing the sky and apostles in triumph.. damn yeah.

--

But also all the aforementioned, of course!
 
How can no one have mentioned the spine tingling
SHE FACED ME IN AWE!!!!!!!!!!!!
off April Ethereal.

Easily the best.

-diso
 
The middle section of the song Deliverance ("Waiting for new disease", etc.). I haven't heard unholy howling like that since Ancient's The Pagan Cycle.

There's a moment near the end of The Leper Affinity where he maintains a long shriek over churning guitars - and then the guitars stop for two seconds while the groan continues. I shudder (in a good way) just thinking about it.
 
Not really Opeth, but in "Crimson" by EoS, after Dan sings "Unholy...", when Akerfeldt comes is and screams "GAAAAAAAAAAAAAAAAAAAAAAAWWWWWWWWWWWD!!".

He hold it's for 15 seconds, but it feels like eternity. Easily one of the coolest sections in any song.
 
i think serenity painted death has some awesome growls on it. my favourite is the "Ripped from my imbrace-ah, melinda reflected in shafts, redline round her neck-ah, met the earth in silence-eah" bit. the riff then is cool too.

I like the growl(s) at the start of breeding death by bloodbath, that fuckin owns, great song too.